I'm unfamiliar with building computers, and I'm just looking for an estimate of price for the possibility of it being cheaper for a better computer by building one. I'm not an intense gamer, practically the only things I play are Minecraft, Mabinogi, and PSO2.
Some things I'm looking for:

Minimum 4 gigabytes RAM, preferably more.
Any size harddisk, preferably over 250 gigabytes capacity.
CD drive doesn't matter, I rarely use disks so it doesn't need to be super good.
I'm not sure what I'm looking for in terms of graphics, the best I can get without it costing and arm and a leg.[/list]

You can get what you're looking for for a few hundred bucks at Best Buy. Cheaper if you build it yourself.

Are you wanting to just build the tower or are you looking for a new monitor and whatnot too?

Specifically, I'm looking for the best thing I can build for 300~600$.

At 600$, the monitor would have to be included in the price.

A good monitor can easily be half that price. But, good monitors don't make or break your system performance.

Buy hard drives with lower RPM's to save some money and 4GB's would be plenty for what you're wanting to do. You'll be able to easily fit it under 600.

I recently built a tower, and if you're willing to build it yourself (It's not that hard, and most people in #cemetech could probably guide you through the process) you can get decent hardware at about these price points. Please note that prices do scale exponentially, so this is not totally exact.

Cases:
- Cheap, flimsy, no frills, but usable: $30
- Okay, fans included, maybe fancy designs, still flimsy: $60
- Aesthetically pleasing, super gamer cases: $100+

Case fans - Don't pay more than $5 each, scan reviews for high CF/M and low noise

Motherboard:
- Lower power, small motherboards that support 2-4 GB memory and 95w CPUs: $60-$80
- Midrange full ATX motherboards that support 16GB+ memory and 125W CPUs: $90-$150
- Crazyprogamerstatus motherboard: Too much

CPU: There is a huge variety
- Cheap but works AMD: $60-$100
- High end AMD: $180-$220
- "Cheap" and pretty good Intel: $150-$250
- High end consumer grade Intel: $300-$400

Memory:
- Decent budget brand: about $6 a gigabyte
- Great high quality brand: about $15 a gigabyte

Hard Drives - DON'T BUY SEAGATE
- Western Digital 7200 RPM platter drives are about $12 per 100 gigabytes
- Solid State drives - About $90 per 100 gigabytes

Power supplies - Plan on spending at least $40. Anything less really is too good to be true. Antec and Corsair make some good PSUs. If you're unsure about what wattage you need, just ask.

Wireless networking - Around $20 for a good card.

Graphics cards - You really do get what you pay for. ATI is generally cheaper than nVidea for comparable performance. You can find great card comparison on Tom's Hardware. I have a Zotac nVidea GT 430 that runs Minecraft, League of Legends, Vindictus, TF2, and CS:S at max settings very well. It cost $70. The gradient is so fine that I won't list all the categories here.

Optical drives:
- CD/DVD Burners / Readers: $20
- CD/DVD/Bluray Burners / Readers: $50-$100

Keyboards - Anywhere from $20 to several hundred

Mice - $10 to $80

Monitors:
- Bottom of the barrel TN displays (Usually 1600x900 resolution or so, 20"): $90-$150 (Cheaper if you go used/refurb). THESE ARE NOT BAD, they could just be better. I have a $95 monitor and it works just fine.
- Decent TN displays (900p-1080p, 20"-25") $150-$200
- IPS displays (1080p) $300+
There are bigger resolutions, but they get really expensive



I built my computer this August and it was about $550 in total. It works fantastic for everything.


Things to keep in mind when shopping for parts:
- The CPU socket on the motherboard has to match the pins on the CPU. For AMD, you might see AM3, AM3+, AM2, FM1, etc. For Intel, you'll probably see LGAXXXX, where XXXX is just a number you need to match.
- If buying old or used RAM, make sure it's DDR3.
- The motherboard has a form factor. Common ones are ATX, mini ATX, and micro ATX. Make sure that it will fit your case.
- Motherboards also have a main power connector. It will either be 20 or 24 pin. The power supply should offer a 20+4 pin connector which will fit both, or a 20 pin which only fits 20 pin motherboards, or a 24 pin for a 24 pin motherboard.
- Make sure you have enough SATA cables from your power supply to power your optical drive, hard drive, etc.
- If you get a heavy duty graphics card, make sure your power supply has a cable for graphics devices.
- Make sure you don't get a motherboard that has AGP instead of PCIe. Make sure your graphics card isn't AGP either.
- Your motherboard may or may not come with SATA cables.
- Your power supply may or may not come with a power cable.
- Your monitor may or may not come with a VGA or DVI or power cable.
- Pay attention to reviews. Don't buy an item with fewer than 10 reviews, or an item that has a ton of one star ratings.
- Read reviews to make sure you're getting what you want.


Hopefully I didn't leave anything out.

$600 without a monitor will get you a solid gaming machine. $600 with a monitor, keyboard, and mouse? That'll be tight, and heavily depends on what you are calling a "gaming machine"

Seeing as minecraft is probably the most computationally expensive thing she'll be running, I think it's easily possible to fit this in 600$.

Phantasy Star 2 is pretty graphics intensive(have to turn shaders off to be able to even play it on my current comp). I'm looking for a machine that'll be able to at the very least handle Minecraft, Mabinogi, Skype, and Chrome all at once. I'm not picky but I want something where everything else doesn't lag to hell when Minecraft is open.

I'll get back with a more specific image of what I'm looking for so we can narrow the cost range down.

I bought my current mouse for $3. It's corded and laser, but it works fine after a year. I like it because it has few internal components such as batteries, it never needs recharging, and the buttons are crisp. I find that many new mice are heavy, making it harder to move them quickly. They also have very short travel distances (which I dislike). Anyway, my 2 cents.

I have noticed the same.

Also, Goodwill, Craigslist, Salvation Army are great places to get stuff like mice and keyboards.

Unless otherwise specified, my prices were new and included shipping =p

My computer can run Vindictus, League of Legends, Minecraft, Skype and Firefox simultaneously fine