My two cents: I've used both MacMall and MacConnection multiple times and never had a problem. I've used both Macs and PCs extensively aover the last 25 years and prefer Macs. With the new Macs you can use both Mac OS and Windows XP/Vista if you provide your own copy of the Windows OS. At MacMall you can even get Windows XP or Vista preinstalled.
MacMall Mac with Windows pre-installed