I have recently upgraded to VMWare Fusion 4 on a Macbook and migrated a Microsoft XP VM. This VM is used to run Quicken and nothing else. Under version 3 I had no issues but Quicken is unusable under version 4. It takes too long to load the VM, the performance of Quicken is so bad that it's unusable. Periodically a single keystroke will generate a string of characters. For example I might press key 'a' and on the screen I can see 'aaaaaaaaaaa'.
There is no way back to version 3 without a lot of hassle so I am exploring Parallels since I cannot use VMWare Fusion 4.
Cheers
Martin Fuggle
(long time Fusion user)