I didn't see this specifically addressed in the forums so I apologize if this is a retread.
 
I have a Dell XPS Generation 3 desktop and need to replace the video card.  I'd like to use the best card available ($250 max).  The Dell support staff tells me that an 8800gts is out of the question given my 460w power supply.  
 
Is this true?  My computer currently has 2 optical drives (cd/DVD), X800XT video card, and a WD RaptorX HD.
 
Thanks for any help.

It probably is true. Anyhow you could try it and if it causes issues (the worst I see happening is computer shuts off) then just upgrade your PSU. I'm not to familiar with power consumptions on current cards. I would like to think that if a 8800GTS wont run fine on that amount of watts then you wouldnt be able to run any other 8 gen cards either. I would just try it and upgrade your PSU if required.

Is that X800XT PCI-e or AGP?
Down load GPUZ.  
It will tell you which interface you have.
 

The best card under $250 IMO is the 8800GTS G92 512MB. It needs 28A on the 12V rails. An OCZ StealthXStream 600W is pretty good quality, small enough to fit physically in some HP boxes (I know because I put one in an HP), cheap, and can handle the 8800GTS. Measure your current PSU (length, height, width) and then if the OCZ would fit in there.

 
It's most likely PCI-E x16 according to this:
http://reviews.cnet.com/desktops/d [...] 74719.html
 
But good point. If it is AGP after all then I suggest scrapping the box and building a new PC.

And, is that Dell old enough that it might use non-standard PSU pinouts?  That is something to check, unless you want to let the magic blue smoke out of everything.

It's PCI-E x16.  Sorry that I failed to mention it.
The computer is getting quite old (almost 4 yrs), but since I stopped playing FPS competitively, I'm in no hurry to start over.  That being said, it might be time.  The processor is a 3.4G P4 Northwood Extreme Edition with 4gb ram if that helps.
 
I had hoped to slot in a nice graphic card and continue gaming to some extent but it's starting to sound as if I'd need to swap out the ps as well if I want to upgrade.
 
I don't know, although by the language of jtt283's I should , about the PSU pinouts.  
 
Are there good cards out there that would be a simple swap?  If I'm going to spend money upgrading yet not get any better, I may as well start shopping for a new rig altogether.
 
Thanks again for all the help

All the cards talked about here will be a significant step up from an X800XT.

I'm sure many/most cards are a step up from a 256mb X800XT, but the only card I've seen mentioned is the 8800gts and the consensus seems to be that it would require a PS upgrade.  What I'm wondering is if there's a graphics card that will run on my system with only a 460w PS.
 
Thanks again.

1) Give it a go with the 8800GT.
 
2) If it pukes, due to the PSU, get a replacement from PCPower, they have Dahell replacement PSU's.

 
 What kind of resolution will you be using ? and what games are you hoping to play ?
 Even some thing that is considered low spec like a HD3650 will be like night and day compared to a X800XT.  
 However I would feel confident you could run a HD 3850 on that power supply Dells are generally quite beefy and you wouldnt need any thing above a 3850 provided you dont want to use resolutions much above 1280X1024, get a 512mb card though as the games these days need it. Im not that up on the power requirements of the Nvidia camp but would guess a 9600GT  would be a good bet.
    Mactronix

There's no replacing an XPS Gen 3 psu, it's a propreitary unit.
460 watts, dual 17 amp rails with a combined output of 32 amps is enough for the G92 GTS, but the cpu would hold the card back.

 
 I knew they were solid but that is really very good.
 From what i could find the machine shipped with a 17 inch screen and if the op is still using that a GTS will be big overkill all round.  
 Mactronix

the watts are fine and the dual 17a should be enough as well.  i have an 8800gt with a 400watt enermax.  the gt requires slightly less juice (26a vs 28a for gts) so that might make a difference if you're on the fence.  other choices could be the 9600gt as mactronix mentions or even an 8800gs depending on price.

I would probably get the cheapest 8800GT you can find. Dont worry about CPU limitations. I ran my first 8800GT on my 3500+ rig with 1GB ram. It ran current games fine! Of course those same games ran better on current rig but not much more than 20% better I would say.

Ok, I'm going with an 8800GT this afternoon as MayDay said it "uses less juice" and I'm not planning to attempt Crysis.  I'll report back on the results.
 
Thanks!

Good deal... I would have done the same thing. Get a AKIMBO cooled one though! If you want to of course. Asus has a nice cooler on them too.

Installed and everything is functioning correctly with a serious increase in FPS.  Thanks to everyone for the help.