I recently bought an ex-demo rev C MB Air (with the 120gb HD) - It did feel slow compared to my other Macs - but I found someone selling a suitable SSD on ebay which was quite easy to fit and has transformed my experience with the MB Air - it is sooo much quicker!!
I was lucky as the SSD was half the price of a new one from the only UK supplier I could find (advertises through Amazon and their own website).
SSDs for the earlier Air's seem more common on ebay in the Uk but if you look hard enough you can find the right one.
My Air has now completely replaced my old Macbook (I use a 1TB portable drive for the iTunes library etc)
I was lucky as the SSD was half the price of a new one from the only UK supplier I could find (advertises through Amazon and their own website).
SSDs for the earlier Air's seem more common on ebay in the Uk but if you look hard enough you can find the right one.
My Air has now completely replaced my old Macbook (I use a 1TB portable drive for the iTunes library etc)