I have it installed on two Window 7 64-bit computers. My experience is only positive. The virtual machine is very responsive; no complaints at all.

Host machines:
OS: Ultimate 64-bit
Memory: 8 GB | 6 GB
CPU: Intel i7 2.80 GHz | Intel Xeon 2.50 GHz

Virtual machine settings:
Memory: 2048 MB
Hard Disk: 130 GB
the rest are default settings