Thanks, everyone. I use it mostly for writing and web surfing (I know, the lowest spec'd air can do these tasks perfectly well) but also for the odd bit of photoshop and FCP video work. I do find that my 2009 machine beachballs more often than I'd like these days, even with 8gb of ram.
My current 2009 model is on the Seagate recall list so I'll be bringing it in soon to get my drive swapped out, and it seems like this would be the perfect time to upgrade my system, if I'll be doing it at all in the near future.