Sorry I didn't realize where you were located (Alaska?). Those shipping costs really suck.
First off, I'm pretty sure the 6800XT is a better card than the 7300GT.
If you're saying you want to make a build soon, why not start it? For now, you could get a decent motherboard that will allow you to get a nice dual-core or quad-core processor, that also has decent integrated graphics. Of course, it will have a pciex16 slot for a graphics card when you save up enough money. I would probably suggest an Intel motherboard with geforce 7000 chipset. http://www.newegg.com/Product/ProductList....0GeForce%207000
. Also, you could get a cheaper Intel celeron dual-core, or if you want to pay $75, you can get a Pentium E5200 dual-core which really isn't that bad, and I heard it overclocks very well.
You can salvage your current hard drive, and as long as you reformat it (wipe it, but back up your data first), you can legally reuse your copy of windows xp (at least I think it may be legal). You could also temporarily use your old power supply, and your case (if the case is ATX, and if the cables for the button to turn the computer on are compatible). Don't forget you can reuse your cd/dvd drive.
All you would really need to buy is:
3. DDR2 ram, which is extremely cheap right now.
If you wanted an AMD build, I could also help you with that too.
This is just a suggestion of course. I really wouldn't waste anymore money into that system if you want to game (especially newer games).
"I think there is a world market for maybe five computers." - Thomas Watson, Chairman of IBM, 1943