I'm not a huge fan of Parallels as a company. I had Parallels 3.0 and the upgrade to 10.6 killed my software. Now they claimed 3.0 and OS X 10.6 were incompatible, but this didn't manifest itself in the "the software will crash occasionally" sort of way, or X feature doesn't work. Instead they wouldn't even let you run the software. When they decide your software needs to be upgraded, you get a lovely dialog saying "This version of the OS isn't compatible, yatta yatta." Their official fix was shelling out $X0 for Parallels 4.0.
And it looks like things haven't changed...
As a result, I'd suggest using VirtualBox. Its been great for me and they don't hold your VMs hostage. I use it for quick sports of Windows dev where I don't want to reboot.
I will be learning how to program through linux and I was wondering if Parallels would be a good virtualization software to shell out money for or if I only need virtual box.
When do they commonly have those?