Got a two month old iMac running Parallels 10 and whatever the current iOS is..

Software update says I can get a free download of Ysoemite. If I do this will I need to re-install Parallels & Windows 8 etc?

Paralells would probably need an update to be compatible and they charge for the newer release.

Your virtual machines will all be intact though and should run unaffected in the newer version of Paralells.

I got tired of the constant pay to update model of Parallels so changed to Virtual box, works fine in Yosemite, unlike my kodak printer.

i recently paid to update to latest version of parallels, it does seem genuinely quicker than 9. Its a totally unknown area for me and i wouldn’t have a clue what to do if I lost it all…

No, you will be fine. Parallels v10 is Yosemite compatible and OSX upgrades are not like a clean install leaving behind a virgin OS. All your settings and applications are left unchanged.

I went to Parallels 10 a weeks or so ago and Yosemite the other day with zero problems on two machines.

jesus, wish I hadn’t bothered! it hangs so much, even on apple stuff like safari, spinning timer for 5 seconds after every click. I’ve got a 3 month old iMac so shouldn’t be a RAM issue with 8gb ram??

Make sure you’ve rebooted it post Yosemite install. Does seem a nightmare without a post install reboot.