Its more a question do I spend the money on an upgrade program for home, or do I wait a little while and buy a new computer with 7 on it.
Of course, the next question I guess I should ask is how long will 7 be supported and should I go straight to 8?
Windows 7 is very stable, and reliable. I have a Pentium 4 with 1 GB RAM that runs Windows 7 right now, without any performance issues. That said, the end date for Win 7 support is 1/14/2020, which is a lot of time in which to eventually upgrade to whatever Microsoft comes up with next.
You can read more about that here: ZDnet Blog