I frequently do this as my secondary drive is a SAN. Having the Program files on the same drive is really not an issue. The only issues you need to be aware of are: Size and Disk Contention. Size is a no brainer. And disk contention will really be an issue if you do lots of read/writes and especially with AS how frequently you are reprocessing cubes. Seperating out your log files and/or having the AS repository on seperate disks could improve performance if there are issues.