Given how many people are insisting on 4GB, I have to think the investment now will pay off later if you plan on reselling.
That was one reason I opted to CTO a 4GB model. The other is that I use it to play CIV5, COD, etc. on the road. I didn't like the idea of running WIN7 with 1.75GB after the 320m took its share of memory.
Definitely worth the extra $100 ($90 EDU) if either scenario may apply to you now or in the future.