Have Parallels 5 in original package. Do I need new vs upgrade to 9?

I have an iMac with Bootcamp enabled with WIN 7 installed. I bought Parallel 5,but never installed, and am tired of rebooting with Bootcamp. Can I install Parallels 5 and upgrade to 9 or will I have to purchase 9 outright to bypass some of the upgrade problems that may occur.
Have 12 GB left on Bootcamp and 140 GB on other side.
Running Mavericks on early 2008 iMac with 4 GB RAM.

 

PDM 5 is not compatible with Mavericks. In your current setup PDM 5 is obsolete, you'd have to get PDM 9 (full price, no upgrade price for PDM 5).
Also, 4 GB RAM might not be enough to run Win 7 smoothly under Parallels.

 

Thanks for prompt reply. Thought my 5 was probably too old. More concerned about my 4 gb of Ram now. Again Tks.