How do I upgrade Parallels 3 virtual machines to Parallels 6?

I have an old Parallels 3 virtual machine that I would like to upgrade to Parallels 6. I already have Parallels 6 installed on a Mac running 10.6.8 (Mac1). I have read article 112283 in the knowledge base. My problem is that I do not have the host Mac that I ran Parallels 3 with anymore. Knowledgebase Article 112283 states that I need to remove anti-virus (I had Kaspersky) and remove Parallels tools but I can't do that because I don't have Parallels 3 installed. I do have Parallels 3 installation disks.

I have another Mac (Mac2), also running 10.6.8, but doesn't have a version of Parallels installed on it. Can I install Parallels 3 on Mac2?

Mac2 is old enough that I can run 10.5.8 on it. I could install 10.5.8 on an external drive and boot from that drive and then install Parallels 3 on it.

Are there other solutions I should consider?

Also, I assume any settings I have for my Parallels 3 virtual machine will still be set if I open that VM with a clean install of Parallels 3. Is that correct?

Thanks