Hello Luz, I have recently done the same thing, I considered Mesh (but there reliability and after sales lets them down), Cube 247 (but they didn't reply to emails and phone calls- and I have seen several complaints recently on these forums about Cube), and Chillblast.
I opted for a Chillblast Fusion Centaur, which got a PCA award a while ago. I went for the 6600 quad, and upgraded to 4 gb of ram.
The only thing I am not too keen on is the Akasa case, but I can live with it.
The delivery took 2 1/2 weeks, and the sales chappy Martin was very helpful and quick to answer any queries.
It's running Vista Premium 32 bit, and so far the only thing I've done was to reseat some cards inside when it failed to boot once, just a bit of newness I think.
I think the specs and components Chillblast use are very good, and even the Akasa case is fine, it's just a bit fiddly if you want to do anything with it, such as replace drives etc. (Obviously this would be applicable to you if you go for the Coolermaster):)
Hope this helps