When I get my new core 2 duo PC I am going to use my old bits to make a HTPC.

I have a K8VSE Deluxe mobo and A64 processor and was going to put it into a Silverstone LC17 case.

But I have seen the Antec Fusion and Silverstone LC11 case and I like the idea of the smaller size.

Is it worth me investing in a new UATX mobo (S754/AGP) or should I just keep the ATX mobo I already have ? What benefits would the new mobo have ?

Or any other cases recommended. Looking for something not massively expensive as its just a 2nd PC.