So I made a mistake.... I bought a graphics card for a pci-e (a geforce 7600 GT) when I should have bought plain pci because of my integrated graphics "card". Once I realized that there was a difference I checked pci cards and found that they were mostly crap (I also found a post here saying the same thing) so I decided to change my motherboard, and maybe upgrade my CPU, so that I could install the card.
1. What will I need to know when picking a motherboard out, and how will I find this out?
2. Is this even wise or am I better off just buying a new computer?
3. What's recommended? Money wise I'd like to keep this project below $400 but higher is possible.
Thanks for your help!

first of all determine what you plan to do with your computer. The PCI-E card you bought is good for gaming, so I'd stick with it.

Then select a decent motherboard. I recommend going with an Athlon 64 series board as they are also good for gaming. I recommend MSI. I do not recommend Asus. I know too many people including myself that have issues with that board. Most new boards (even the basic models) contain most of the bells and whistles an average person would need. The next step is select a high end chip that will last a while. You're NOT going to find a CPU let alone other parts combined for less than $400. A decent Athlon chip low end will run around $300 plus other parts add around another $200. I recommend swinging an extra $300-400 and get a top of the line CPU so your motherboard won't be obsolete tomorrow. You can salvage a CD rom drive, floppy drive etc... your memory is cheap and 1GB will run about $75 or less. ensure you BUY the correct memory for your motherboard. READ the manual from the motherboard BEFORE buying.

Will my case fit whatever motherboard I pick out or am I going to have to buy a new one too or find the right size mother board? Plus what are the parts I'll also need to buy when I get a new motherboard? Power stuff like that? Where to buy is another thing, I've been looking at tigerdirect. Thanks again.

Are you in the US? www.newegg.com is one of the favorites to buy from. Good prices, fast delivery and amazing customer service.

We need to know your case's "form factor". ATX is a common one, but this determines what size motherboard you can use. Depending on how old your case is, it may be reusable.

Does it have a make/model number (usually they don't). Open up your case and take a picture of the guts for us. Another possiblity would be to measure your motherboard length and width and post it here for us.

Before you put it all together, you're going to want to do some homework.

Here is a pretty good starting point: http://en.wikibooks.org/wiki/How_To_Build_A_Computer

you can make a pretty decent rig for about 500, thats without a monitor.

you have to get a case with a power supply, 1 hard drive, 1 motherboard [gigabyte or asus], 2 sticks of 512 ram, you need to know what kind of ram your mobo will support, a dvd rom or writer, a floppy drive. you already have a video card. definately go with a amd processor, there around 150 for a athlon 64 3200+. you probably want a higher one for that video card, and a 400 watt psu. its gonna take a lot of time chosing the right parts and once you get it all its gonna be diffucult putting it together since its your first time. you can get a pretty decent comp already made at newegg. for around 500, no monitor again. remember this is for a budget build, like you said.

If your last computer is a "branded" computer (Dell, Compaq, HP, etc), chances are you probably need a new case.

Be caerful which PSU you're going for. Stick with Antec and you should be fine. I'm not too privy with PSU makers, so there might be some other brands which are equally good. There's probably a good thread about it anyway somewhere.

I personally like to stay with well known m/b brands, especially since I see alot of problems from users of less well known brands all over the net. They might have some good ones, but MSI, gigabyte, and definately Asus, should be m/b brands you can go for (I'm not listing really high end only m/b manufacturers).

As for RAM, just go with normal speeds (usually the fastest your m/b can support). The slower RAM isn't much cheaper, and at the same time, not much slower neither. Main thing is to buy from trusted brands. Can't go wrong with Kingston/Corsair/Mushkin/OCZ/etc/etc/etc. Tons of brands these days, Kingston and Corsair being the favourite. Just don't buy something thats says Generic.

I think everything else (except CPU) can be salvaged. Or added later without much of a problem.

However, HDD is pretty cheap these days, so you might want to look at 200-300gb disks (the current sweet spot).

Of course, compared with unbranded goods, you will get much lower prices, but there's a chance they'll give you troubles, and we'll see you back here debugging