We tend to split things up on Application Servers.
OS C: 100 gig
Data D: 1.5 tb
This allows us to install QlikView on the D drive and also create a QV Data Folder on the D drive to host our QVD's, QVW's and also our Log files and such. You just need to make sure you have enough disk space if you are going to put everything on C.
We have run both AMD and Intel. Mulitple Cores is the key and as Bill said do not underestimate Memory and Processors. QV loves both.