It might be useful to know what you find the limitation of your current software is, what you are trying to (solo vocals? acoustic guitar? electric guitar/bass? whole band? (what instruments), symphony orchestra?) and what interfaces etc. you own or whether you need to/plan on buying another interface -- that way people here can better help you make a decision, otherwise we are all just guessing. But as a guess the most logical upgrade is likely to Pro Tools 10. However I doubt that "SE 8 something" will qualify for an upgrade/crossgrade and you'll either have to buy a full retail packed software for around $699 or you need to buy a bundled interface that comes with the software like an Mbox Pro or Eleven Rack. If you are a guitarist, seriously look at the Eleven Rack.
Pro Tools 10 in the Avid Store:
http://shop.avid.com/store/product.d...07527273768544
Upgrade options in the Avid Store (I doubt your software quantifies):
http://shop.avid.com/store/product.d...07527273741024
The Pro Tools HD family products require proprietary high-end hardware interfaces and you can get into those starting around $5k-$10k, my usual axiom is if you don't know you need Pro Tools HD, you don't.
Avid often announces new product around the AES conference, which is later October. Who knows if they will announce new stuff there this year. If you don't need to buy in a hurry I might wait.
Darryl