After buying the disaster that is WinTel, I gave this a try.

It is quite reasonably priced, and works okay with DOS or Win98 on a G4 PPC. Whilst performance and features are nothing spectacular it does indeed work pretty well. I could not get it to run Windows NT, and I didn't even want to try XP, but there are a lot of current programs that will still run on Win98. This is a worthy effort and as long as your expectations are reasonable, this is a pratcial way of running those few programs that you absolutly need windows for.

I recently got Virtual PC with MS Office 2004, since it was on a special and I basically got Virtual PC free. I can say that XP Pro on VPC is about equivalent to Win98 on GuestPC. So Virtual PC performs better and has some useful options, but is more expensive.

If you want a balance between price and performance and can live with Win98 (and indeed have a copy you can use), and are willing to live with the basic feature set, I can recommend GuestPC. If you have a little extra cash, Virtual PC is definetly worth the extra, with features such as state saving and pausing which means you can have a windows session ready to go anytime without tying down your CPU. (My iBook is unusable for anything else whilst using GuestPC, whereas I can have VPC running in the background without things grinding to a halt.)

Ultimatly Guest PC is a stable, resonably priced program that does what it says on the tin (and not much else). Even though I have now moved on, I don't regret the purchase, it served it's purpose for me.