upgrade videocard or videocard+mobo+CPU?

[rmr]

I want to upgrade my computer so I can play the latest games, it is the computer listed below in my signature. I'm thinking of a new motherboard,CPU and videocard, but I don't know what a good combination is. Would like something cutting edge so I can play new games that come out in the future. Price is not important.
So here are my options, 1. just buy a videocard and leave the rest of computer alone.
2. Buy new videocard,motherboard and CPU, use my existing
drives,case,etc.
3. Build a new computer just for gaming.
But I don't really have room for another computer+monitor.

Also am I going to need a higher rpm hard drive for best performance?
I'm not up to speed on what parts are the latest and greatest. I need a good parts list for which ever route I decide to take. Any help will be greatly appreciated.
Thanks!

[blue60007]

Your CPU socket and AGP is a dead end, I don't think there's much sense in putting more money into a dead-end system.

What exact power supply is that? or if you can tell me if it has a 24 pin main connector? You might be looking at a new power supply too.

You'll need at least a 7200rpm drive...a 10000 rpm drive speeds things up some, but it won't help with gaming performance.

I would look at a Socket 939 system so you can re-use the RAM. First though, what is your budget?

If the budget is a little tight, you might look at this:
http://www.newegg.com/Product/Product.asp?Item=N82E16814130274
Then again, you could keep saving until you have enough for a new build (or mostly new).

[glc]

If you don't want to do a complete new build, just get yourself a 7800GS AGP card and run it some more.

[rmr]

Thanks for the help guys, I think I will go with a 7800 for now.
Sounds like it will do what I need and will do another build in the future.