I am building a computer with the following specs and i am just alittle concerned that either the heat from the graphics card will be too much for the shuttle case or that it wont be sufficient power to run all the 3d cad and design software its being built for.

Shuttle XPC SX48P2 E with built in mobo
Built In - 450w
Intel E8400, Dual 3.0 ghz
Kingston 2X2gig 800m
Seagate 750ig Sata
Samsung DVD RW Sata
Asus EN8600GT
Vista Business
AutoCad
Dual DVi 22inch Samsungs

Would appreciate any responses to whether i am worrying about nothing or even if anyone here can think of something that might be better for me to use