I've been using VMWare Workstation for several years and love how it allows me to setup different operating systems on my workstation for evaluation, test, special connectivity, or software installation and operational testing without any risk to my base OS installation. Now that Microsoft® has bought and re-written the Connectix Virtual PC product and released it as as Virtual PC 2004, it's worth checking out this a nice flyoff of VPC2004 versus VMWare's Workstation 4. Looks like VMWare is still the performance champ, but at twice the cost, I guess you get what you pay for.
Bob Baker