Rehousing a Dell computer

I have a big 4 year old Dell Tower that I'd like to rehouse in a smaller, more practical case. I was told once by a local computer store employee that Dell, HP, Gateway, and most of the mass produced brands use proprietary motherboards and other components that make rehousing them difficult.

I'd like to use a case like this. Not necessarily this specific model, but something along those lines. What components would I be able to reuse from my existing computer and what new parts would I have to buy?

Here's a list of my PC's specs:
Pentium 4 3.0 ghz
1 gig DDR SD RAM
160 gig SATA HD
120 gig SATA HD
Samsung DVD+R
Sound Blaster Audigy soundcard
NVIDIA FX 5200

I looked at the type of case you were interested in. It is a small form factor case. Generally speaking it is intended for use with small BTX motherboards. I've seen them at Fry's Electronics. There are other larger cube style cases made for micro and standard ATX motherboards. Of course, they are larger cubes.

Does your Dell computer have a very small BTX, micro MATX, standard ATX, or large EATX motherboard? As B-Unit suggested find out which size Dell motherboard you have, then look for a cube to match.

What are you using it for?