Not the same obviously, but..As said matey, its all about what you use it for.
MBA will be superb for day-to-day affairs.
Just to compare, I have had a Sony Vaio TR1MP, 900mhz Centrino - 1GB - 30GB 4200 -.
This was brilliant for surfing, chatting, music and photo's. Ya know, normal stuff.
If thats all you use the MBP for then go for it, and pocket the cash.
I have an Asus Eee which is 900mhz (700ish), 1gb ram, 4gb ssd and a SD Card for more space, and it runs FM2008 just about, i use it a lot at college for Excel, Access etc.
The Air looks good for just browsing and general use.
If it were me, and i had an external hdd, id get the Air.