I had two big complaints with Parallels that led me to consider dropping $80 on VMWare Fusion instead of, say, beer. First, it was incredibly slow and resource hungry, and I'd have to quit almost everything to run my Win32 virt. At the very least, I'd have to quit Firefox, which was really annoying. Secondly, the damned taskbar was never visible. Every time I booted, and more, I'd have to go to Start, Settings, Taskbar and hide, apply, show, apply. Augh!
After experiencing completely lovely performance under VMWare Fusion, I updated my Parallels virt to use the same amount of RAM. VMWare was using 512 MB, which it suggested was ideal. I had upped my Parallels machine to 768 or so, although I think it also claimed 512 was ideal. I lowered its memory usage to 512 and its performance increased by leaps and bounds. Wow!
Then I googled around for the stupid task bar problem and found out that it's a feature! Ugh! I went to the Parallels menu bar and took Applications, then Show Windows Taskbar. I guess it has something to do with the Coherence mode, where you only see Windows applications, and not the desktop. I never use that.
Anyway, now Parallels is totally usable, it seems. It's certainly not worth spending eighty bucks to replace.