I have just the same Macbook you have, except I got mine in late 2006, and I updated it to 2 gigs of RAM. A week ago, I bought an Air (128 SSD, 1.86, 4 gigs of RAM, refurbished it was $1260 with tax.)
I have to tell you, I find it just delightful. I had a real mental block about buying a C2D computer that on paper, looked less powerful than the one I already had (1.86 vs. 2.0 in my old Macbook.) I decided to take the plunge based on the positive things I've been reading here. I have not been disappointed. I am so pleased at how quiet and cool and light it is. (My usage is mainly word processing/surfing/movies/Flash-based games.) I love the battery life. The screen is so bright I have to turn it down halfway just for comfort.
And you already know, I'm sure, how speedy the SSD is. I've also installed Parallels and it works with no problems. I haven't had problems with stuttering -- the prior poster who mentioned that problem has the older version of the Air.
There is something to be said for "future-proofing." But the people here who are most concerned with that are probably doing far more with their computer than I will ever do. I'm not a power user and I love this form factor.
My one slight regret is that maybe I should have gotten the 256 gig configuration, but you know what? Right now I have 45 gigs to spare, and I've got external drives. I'll make it work.