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?
You're going to have a harder time getting 7, the longer you wait, since MS wants everyone on 8 now. If you have a computer old enough to still be running XP you are likely due for a full system upgrade anyway.
Mainstream support for Windows 7 ends next January. Extended support ends in January of 2020, so patches will continue to be produced for a long while yet.
The current version is 8.1 which is supposedly an improvement over most of what people hated about 8.