Need help finding PSU for my HTPC - Dell Optiplex 780 DT

I've probably spent days researching different PSU's and graphics cards copatible with this computer.. I would sure appreciate any advice.

Here's what I'm working with:

Dell Optiplex 780 DT (not Mini Tower or SFF one - its kind of a cross between the two and the case size presents problems with PSU - Also the mini Dell motherboard connector - wont work with most PSU.

I am trying to A) find a 400 or 450 watt PSU that will connect to motherboard (fitting in case would be nice however I am open to having the PSU outside the case if need be B) will a Sapphire Radeon HD 7750 1GB DDR5 Micro HDMI/DVI-I/Mini DP Low Profile PCI-Express work with the motherboard - i know hyperspin doesnt require a high end vid card however i wanted to see if PS2 roms would play smoother and possibly some games - primary use is for XBMC and Hyperspin

(see below specs)

Specs:

http://i.dell.com/sites/content/busi...tech-guide.pdf

Intel® Core™ 2 Duo E7500/2.93GHz, 3M, 1066FSB <-- DT is the case size (i have this mb see specs)

The PSU is killing me. I know they make ATX 24/20 pin big to mini adapters but Dell has dif pin settings etc. .

Any help would be greatfully appreciated.


-CBT