I don't mind doing the leg work myself, I just need to know what to look for. If I went on Newegg I am sure I would buy the wrong thing, so if you let me know some good things to search for (which you did ) it'll save me a lot of trouble.

Quick question: My comps product info clearly states it can't run more than 2 GB of RAM. Why is this? Is it a design issue, power issue, what? Is there a workaround in case I want 4 GB one day, or will I need to start over from scratch?

Only 2GB? It's certainly not an OS restriction. I'm assuming it must be your MoBo then.

Do you have the exact make/model of your computer? Find a link if you can; I'd like to know more about the motherboard.

If it weren't for that, I was going to recommend this:
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231145

I already have one kit that I purchased about 6 months ago and was planning on picking up a second since I started using X64 Vista. $45, DD2 8000/1000mhz. Great modules, rock solid stable (I overclock). Very well received by the people who have bought them.

As for VGA cards, check the following deals on HD4850s. They are all at/under $150 (some with rebates, some without, some well under $150 w/ rebate).

Sapphire (well reviewed, good manufacturer, good benchmarks, great price)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102770

HIS (well reviewed, good price, current special deal w/ memory purchase)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814161235

Gigabyte (good brand)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125238

MSI (good brand)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125238

Powercolor (great price, few reviews, looking good so far)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814131125

http://www.shopping.com/xPF-Gateway-Gateway-GT5411E-Desktop-Computer-Bundle-With-Intel-Pentium-D-Processor-915-19-LCD-Monitor

It's a Gateway GT5411e. I put the info in the OP, but here's a link to it's page. I'll add on if I can find anything else on it.

I'll definitely look into these things and see what's best for my budget while still getting my money's worth.

GT5411E: looks like 2 memory slots (as you mentioned), with each only able to address a maximum of 1GB.

That's kind of a big crutch if you're running Vista. It's okay for gaming if you turn off a lot of system services and background apps, but far from ideal.

You're still okay w/ 2GB (you'll have to source a 1x2 kit instead which should be really cheap).

Personally, I've built a Vista gaming system with only 2GB of memory (using DDR3 1600mhz modules that were simply too expensive to stay in budget if I went to the preferred 2x2GB module set up), but I did have to gut some OS functions to leave the max amount of memory available for game engines.

Kingston PC2 6400 for $12 per 1Gb module (free shipping)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820134114

Great brand, unbeatable price. Not going to get any better than that.

So should I be getting one or should I get two and replace what I have inside?

Yes; buy two. Always used matched sets of memory modules whenever possible.

I think you should just buy an HD 4670 and that ram that other person mentioned. That will get you up to a pretty good gamer spec for the next few years at least. That card is excellent I use it in my HTPC because AMD cards can output sound via HDMI (dongle) and it works really well. Its got 2x the shader power and 3x the texturing of an Xbox 360 so it should do you just fine.

This should run you up to about $120 incl shipping for both ram and the graphics card. If you go any higher you'll need to buy:

• A new CPU
• A new PSU
• perhaps even a new motherboard.

K.I.S.S.

Update:

I need to hold off on a videocard, but I need to increase the memory so Vista runs better. It's getting on my nerves. Should I go with what was mentioned previously, which is the Kingston two 1 GB sticks of memory? Also is there any way for my to change my setup so I can put 4 GB in there instead of 2 GB? Maybe replace the memory slots themselves to ones that support 4GB?

Aren't the new lines of video cards coming out some time this year? I'd wait until after they hit to upgrade because that's when you can get the most bang for your buck, usually.