Rather then post it as my own info I'll provode a link to,
"Dell XPS 410 and Geforce 8800 GTX Horror Story"http://www.tomshardware.com/forum/53061-2-...00-horror-story
If you do decide to go with another power supply make sure it is "Dell compatible" .
I suggest looking for a video card that doesn't require "extra" [or very little extra] power.
I don't know what a good alternate nvidia card would be because I don't use them.
If it were me I'd go with a Radeon HD 2600 XT,http://www.newegg.com/Product/Product.aspx...N82E16814161203
I have one of these, it's pretty decent as far as I'm concerned.
Or a Radeon X1650 http://www.newegg.com/Product/Product.aspx...N82E16814161258
It's a little older technologhy but has pixel shader 3 .
Either of those would be a real step up from what you have.
If you want to look for a nvidia card that doesn't require a
extra" power connector here is a pretty good list of video cards,http://whirlpool.net.au/wiki/?tag=rmp_vds
OCZ StealthXstream 700W,Gigabyte GA-EP45-UD3R , E8500, Arctic Freezer Pro 7, 3GB G.Skill PC8500,Gigabyte Radeon HD 4850 OC [1GB ], Seagate 250GB SATA II X2 in RAID 0, Samsung SATA DVD burner.