Psu compatibilty

Hi I want to upgrade my dell 8400 psu in order to install a better graphics card like an ati radeon 1550 512 megabytes. But becuase dell compute's are temperamental when it comes to upgrading im unsure whether i should bother upgrading in the first place.

I have found a psu that does say it is compatible with my dell model and here is the link http://www.pcpower.com/power-supply/silencer-470-dell.html

Please let me know if you think it will work with my dell and if i was to upgrade my graphics card with that 470 watt power supply then would most graphics cards run ok? Thank you

Thats just what i wanted to hear lol thnks been looking all over the place for psu's and started to lose hope...if i was to buy this and it was compatible do you think installing a graphics card would be ok aswell because i heard dell systems can lock up sometimes when upgraded...:S

Thanks :)

your dell one of these:
http://www.pcpower.com/power-supply/silencer-470-dell.html

then... I guess it'll work if it's on that list.... Usually what dell does is change the bracket plate to where they scramble up the screw holes, so you can't use an over the shelf model without some metal cutters and a drill. They may have also changed the power connectors on the motherboard so that only there PSU's can be plug in, but I'm guessing on that one.