Might I ask why you're getting an original MBA and not a newer Nvidia model? Have you considered the vast improvements in the v 2,1 MBA over the original? I believe the vast majority of people will receive far more value in paying a little more money for a v 2,1 MBA over an original MBA.
Unless you're only planning to use the MBA as a word processor, it's not wise to go with the original MBA, in my opinion.
You're not just missing out on DDR3 RAM. The biggest thing you're missing out on is an Nvidia GPU, at 5X the performance of the original MBA. You're also missing out on a much superior and cooler running Penryn CPU, a SATA-II drive controller, 50% more drive space in a SATA HDD drive, and even the capability of driving a 24" to 30" Apple Cinema Display.
I would highly advise you consider all of the improvements of the v 2,1 MBA and also the very low added costs to buy a newer MBA over the original model. In addition, the last time the MBA was updated it provided not only a few small spec bumps but also a HUGE drop in the price. There is a possibility of another drop in the MBA pricing with its next update which could further lower the price of newer MBAs on the secondary market. That update could happen within the next few weeks.
I would strongly suggest you consider the additional costs and get the far superior model MBA. It's not just 62% faster RAM in the newer MBA. It's a completely different system that provides a completely different experience and far more capabilities to the MBA owner than the original MBA provided.
Good luck with whatever MBA you ultimately end up buying.