I own a Lian-Li PC67USB, very nice looking and great cooling.
Previously, I have my Athlon 1.2G@1.4G in the Lian-Li, CPU Idle 48c, load 53c. Recently, I moved my whole Athlon system from the Lian-Li case to INWIN S508, the temperature goes up to CPU Idle 53c, load ( never dare to try ). I am ordering a Alpha now for the Athlon to stay stable in the INWIN. I have same number of fans in both case ( front, back, etc). And, I feel certain that Lian-Li Aluminum case provide much better cooling than normal steel case. BTW, if you are curious, I use the Lian-Li for my new 1.6A@2.4G P4 system, retail HSF, CPU Idle 37c, load 50c.
Also, Lian-Li case is very good handling, never need to use a screwdriver except for taking out of CPU fans on Athlon, and I like the idea of taking the whole motherboard out with the secondary back panel plate attached.
The cons: It is a little bit louder though.