I’ve been extremely happy with the Case Logic 13″ Laptop Shuttle sleeve (SKU-SNS-13). It’s an almost perfect fit for the 2710p. It fits fine with the media slice attached, though if you had both the slice battery and media slice it might be a bit too snug. The AC adapter fits okay in the front pocket, though it does create quite a bulge. I generally don’t carry it with me given he long life of the 2710p’s primary battery. The sleeve fits perfectly inside my regular laptop bag and the zippered sleeve just becomes a pouch inside the top-loading bag. When I’m going to a meeting, I just slip the sleeve out, leaving the bulk of the bag in the office. If I expect to be out for several hours, I’ll take my spare primary battery with me in the front pocket.
http://www.caselogic.com/13_laptop_shuttle/product_detail/index.cfm?modelid=70111

The waterfield sleevecase is a superb laptop case, at least it has been for my experience of taking my Lenovo X61T to and from work every day. Perfect light weight but (relatively) safe way to transport just the laptop. Add the Piggyback case, and you can transport your extra battery or powersupply.
Travel light and work light!