Currently Being ModeratedJun 27, 2012 9:55 PM (in response to michaelfromseal beach)
A lot, at least for now. And here's why. 32bit programs max out at 4gb of RAM. A lot of the programs we all use are still 32bit.
If one of them decides it needs to use all the RAM it is capable of, then you'll get swapping between the disk and the RAM. The SSD's in an Air are fast, but still much slower than RAM. If you have 8gb, the OS will generally still have plenty of RAM to do its business, as well as any background processes while your memory hungry app is done with about 4gb.
This is all a gross oversimplification, but in practice it's pretty accurate. Breaking the 4gb is just a nice thing to do if you can.