I'm now on my 3rd Mac laptop in the past 12 years - currently using a 13" MacBook which also has full (via Bootcamp) Windows XP loaded by my IT people, which makes me fully connected to work (Hurray )

As others have posted, the current Macbook is the way to go in new Apple laptops, and you can get excellent deals on refurbished (but still fully warrantied) Macbooks at the online Apple Store. If you absolutely must have a new laptop, and have a University affiliation (and I'm not sure how closely they verify these things) you can also click through the Educational area of the Apple Store and save $50 to $100 depending on the laptop. The other thing most people don't realize is that Applecare (the extended warranty) is also discounted for Educational customers. Use the money you save to upgrade the RAM.

If you don't mind truly used (ie not eligible for extended warranty) and you want small, look for a used 12" Powerbook which at 4.6 pounds was the lightest Apple laptop, and likely to remain so for the foreseeable future, or a 12" iBook which was a few ounces heavier but will be more affordable (if you can find one). Both of these with appropriate RAM upgrades will handle the work you've described.

Murm