dell case / motherboard switch

Hello all,

Our "spare" pc is a Dell Dimension 8300 that crashes randomly. We believe it is a power issue, but of course the Dell case is not standard ATX so we can only buy a replacement power supply from Dell. The highest wattage replacement for my model is something like 350w, which is way too low for the video 512mb video card I'd like to install (a hand me down from my main pc upgrade).

So I went out and bought this case (I liked that it came with an installed 480w power supply and for $35 couldn't beat it): http://www.microcenter.com/single_product_results.phtml?product_id=0334041

It says it supports both mATX and ATX, with the largest motherboard supported being 12"x10".

Now, a simple glance at the back of my pc and I can tell the layout of the components wouldn't work in the new case (which I expected). But I have to get a new motherboard anyway to use the video card anyway.

Any recommendations? I'd like to still use the current processor (Pentium 4, 3.0), but I'm sure I'll just buy new ram.