Do I even need to upgrade?

I have 10.6.8 Snow Leopard. It’s doing everything I need here: VMware 3 using Windoze XP, SQL Server and Crystal Reports all work perfectly, sharing Mac folders. So why upgrade? VMware 7 won’t go on 10.6.8, I don’t think. Is it easy to go to Yosemite (and keep using VMware 3 or does it need an upgrade to 7?) Will I lose my apps or files? Will XP still be usable? I have a 2008 Mac Pro 2x 2.8GHz Quad Xeon model. Mike Bird

There’s certainly a strong argument for not fixing things that ain’t broke. But both Snow Leopard and Windows XP are no longer supported by Apple and Microsoft respectively. That means no new security updates and, for XP especially, that may be a concern if your Mac Pro is connected to the internet. Any viruses or trojans you pick up in Windows can’t cross-infect OS X, but they will affect you all the time you are running Windows and can spread to clients or friends. But on the other hand, the upgrade to Yosemite, Windows 8 and VMware Fusion 7 is big enough that I would be strongly tempted to upgrade the Mac Pro as well.

Your mention of SQL Server makes me think that this machine is used for work and I’d be very nervous of changing so many things at once on a computer that I used to earn a living. By starting with a new Mac, you can keep the old one running, and set up the new one running alongside until you are confident you’ve ironed out any kinks.