I am think of upgrading from my 1650 Radeon 512 128ddr2 to an nvidea card soon. I might even go crazy and go SLI. I am a total SLI noob though. I also hear that one good card does better than 2 midrange. So the Q is...

If I get a DX10 video card, can I use it on xp? Also, I don't think I can use dx10 on xpPro. So can I install dx9 even though I have a dx10 card? Please help!

I also don't plan on buying vista anytime soon. Should I just get dx9 cards?

You can use a DX10 card on XP, but you won't be able to run games under DX10, as there is no DX10 available for XP. But you can install DX9 and it will work just fine. I have a DX10 card and use XP for gaming, will only use Vista for Bioshock.

Good! Bioshock is going to be amazing. Have you played System Shock 1 and 2?

So is bioshock going to need dx10? Should I get dx10 or dx9?

Never played SS1 or 2. Bioshock will make use of DX10, it will also run under DX9, as probably all the games using DX10 that will come out in the next two years or so will. The difference won't be too great though, so you'll get plenty of eye-candy with DX9.
If you plan on getting a DX10 card, don't get anything below an 8800GTS 320. If you'll buy a DX9 one, an X1950XT would be the best choice, or if you don't have money for it go with a X1950PRO/7900GS.

It sounds like you're a bit confused,let me try to explain.
XP uses DirectX 9 to play games and cannot use DX10
Vista has both options DX9 and DX10
Nvidia's 8800's have both DX9 and DX10 and can be used in either XP or Vista.
If you want to play any game in DX10 mode you have to use Vista.
Though its hard to do,especially if you have the money for it now....
You should wait for the new cards that are said to arrive this Christmas.
They are said to be twice as fast and will support DX10.1 wich the current 8800's dont
Eventually in a year or so you'll probably upgrade to Vista and by then DX10.1 will be out.
If you wait for the new cards it will save you the trouble of upgrading again cus you'll have DX10.1 already.


Heres a link on what I'm rambling about

http://www.xbitlabs.com/discussion/3953.html

Good rull of thumb IMO: If you don't know whether you need SLi/Xfire or not, you probably don't for now.

As for the rest, I think you have most of the info you need, but the main thing to remember is that DX10 is optional, but only available on Vista, DX9 path is available to both OSs and any DX10 card you consider as well as your current card.

I'd recommend waiting for the game that makes you want to leave the X1650 and upgrade with the target of that game in mind.

But if you do upgrade and don't plan on moving to Vista anytime soon, then you will be on DX9-only path, and your card will likely do a damn fine job at it as long as it's a GF8800 or HD2900 series card, anything less IMO is not worth the 'upgrade' from what you currently have, unless you're getting it for free.

yeah... don't do what I did and fall for the marketing of the 8600's