Heres the deal: On the Blackbook I had just before I got this MBP (a month ago) I had XP dual booted and it worked great. Now I need to be able to go back and forth more easily between Windows and OS X for work so Im about to run grab a copy of parallels 5 and Win7. Current set up: 09 MPB 4gigs RAM intel 80gig SSD boot drive. Hitachi 7k500 HDD -How exactly does Parallels Work as a virtual machine? Does it create a permanent partition that it runs on every time you start the virtual machine or does it do this on the fly every time parallels is started? If it DOES create a virtual partition every time its ran does the virtual partition run entirely in RAM or does it write to the HDD? If it DOES create a virtual partition and write to the HDD can parallels and Win7 be installed on the HDD instead of the SSD? Reason I ask is I have had some programs tell me that they HAVE to be installed on the boot drive. the boot drive being the SSD. I don't want to install everything on the SSD if there is going to be a lot of writing and erasing for all the obvious reasons with the SSD. BUT, that being said, if I did put everything on the SSD, would Win7 and the TRIM command take care of all the writing and deleting that parallels will do assuming that is how it works ( based on the questions I asked above?) Just wondering if anyone with an SSD AND HDD had any tid bits on how they did this.