Hi Steve_j
Using Parallels 7 here, running Lion 10.7.5, and Windows 7 Professional. Works quite well, and certainly runs at more than acceptable speed.
IAW Paddy's and Tacit's remarks for the most part, being an end user here of Parallels. When I made the decision between VMWare Fusion and Parallels, at the time it certainly seemed that Parallels was more consistently maintained than VMWare. I did a lot of digging around for reviews and posted about it here at TS.
That may not be the case now, but I haven't really looked around being pretty happy with Parallels for the most part. Since I bought the program in February, there have been 3 updates, and for what I'm using it for, which is to run a few Windows programs, and mostly, a Java-based beverage ordering system that is web-based, it's been very stable. I did run into a display issue at one point, but reinstalling Parallels tools seemed to cure the problem.
Paddy's pricing is correct, however, occasionally Smith Micro and Nova Development run software bundles on deals, and if you decide on Parallels and are able to wait a bit, you might be able to snag it for $49.95 on one of their bundles.
Also, no matter which program you choose, it may be a good idea to max your RAM out, as any of these programs can be RAM intensive, depending on what you're running on the Windows partition.
HTH,
Chris