Can I get away with sticking an ATI Radeon HD 4670 graphics card into one of these things? I haven't gotten one yet, however, I do have the graphics card readily available. Will I be able to put it in, like does it have the special ports for it, or will it even fit?
(The reason I want to do this is because my main computer just died and I found one of these Dell Optiplex computers with a 3.4GHz processor)
Yes you do need the low profile card. Also you do realize that the MHz aren't everything? That Optiplex 745 is an old machine that would get outperformed by any current generation CPU from AMD or Intel (Athlon II, Phenom II, FX, Celeron, Pentium, i3, i5, or i7).