I have been reading about how paralells desktop 7 will not run in maveriks, and one needs to upgrade to version 9. This feels like a ripoff to have to keep buying this software over and over for each mac OS change. Does vmware fusion work the same way? does one have to keep buying upgrades to work with each new version of mac os? are there any equally free vm software for the mac? are they reliable and as good as paralells? If installed the free versions, can I transfer my windows installations over to the free vm software? or would I have to buy new copies of windows as well?