I am having major computer issues. I used to be able to run 40 or more tracks of audio with effects. Now I play one track and my disk is at 60% and starts to stutter and sometimes stop. I run XP and Microsoft is no longer going to update that OS. I was thinking about going with Windows 7 and wiping this computer clean. What does that mean as far as all the Sonar updates Ive purchased? Can I still use them or can I get a 7 version at a discount?

If the machine is struggling with XP, it may not run any better using Win7. Better to determine what is causing the problems on the machine before spending any money on it. Start by checking the windows logs for clues.

Buy a new computer, you'll love it! I fought with the old xp machine for years too, life's too short wasting time watching your pc spin on something. For all those tracks, go with at least 4 or more gigs of ram (I think 8 and 16 gigs of ram is common these days), it takes almost 2 gigs just to run windows 8. Check out the refurbished pc's at Microcenter, you can get nice ones for $300.00 http://www.microcenter.com/ choose your store at the top, then click the green button on the left that says "refurbished."

It would be nice to know something about your PC when trying to think of possible solutions.
Do you defrag regularily? How much free space on the hard drives? If there's less than about 15% free space, it may be the disc doesn't function properly, and in the worst case, it can not even be defragged. How old are the HDDs? Could they be coming to the end of the road (you have backups in order, don't you?).
 
"What does that mean as far as all the Sonar updates Ive purchased? Can I still use them or can I get a 7 version at a discount?"
If you mean SONAR 7, (not Win7) then no. Version 7 hasn't been available for over ten years, but you can get X3 a little cheaper.

2 week old thread with no info from op