PSU should work, 24 pin EPS 12V, ATX compatible.

Dell - Support

Check out maybe something like this?

Newegg.com - CORSAIR Enthusiast Series TX650 V2 650W ATX12V v2.31/ EPS12V v2.92 80 PLUS BRONZE Certified Active PFC High Performance Power Supply

or you could probably get away with a 500W. Unless you plan on someday going crazy with modding.

Edit: Dell link doesn't work, just goodle XPS 8100 board specs