I covet this accessory for my laptop.

Not the sort of thing you've asked about, but Velcro cord wraps are indispensable (and I despise Velcro for the damage it does to fabric. I remove Velcro clasps from any bag I might accidentally carry and I cannot recommend these doo-dads enough). Blue lounge has cord catchers for use while your laptop is on a desk, as well as nice cool feet.

I suggest, if you've got storage at school, that you buy one adapter to store at school and one to store at home. The power cord weighs so much more than the laptop, but having one handy is so useful!

Definitely an extended or fast response warranty, with onsite service if you can get it. If the laptop goes sideways and you have to ship it to get it fixed, you could be computerless for days. But, don't worry about this if you know you will have local support or repair. DO worry about this if you bought the laptop at Best Buy or equivalent highway robbery outlet.

An accidental damage plan is important if you're clumsy and/or expect to be banging it around and Lojack if you're concerned about theft. Lojack's more important for remote wipe than recovery, IMO.

Large batteries are good to have, but I'd spend money on a replacement plan for the batteries instead. Those suckers are expensive.

I definitely second getting an additional power adapter.
A small external hard drive for backups.
A bluetooth mouse if your laptop supports it.
Also a bluetooth earpiece.
Skype and a headset with mike (bluetooth if you can) if you'll be calling home.
Software-wise, if you dig the MS stuff, office 2007 student teacher edition, otherwise OpenOffice.
A good antivirus package like avast or nod32.
An extra USB male to mini cord for your external hard drive/USB charging needs.

Get some sort of board to set it on when you're using it on your lap. I use an old wooden cutting board, but there are purpose-built insulated things you can get if you prefer. Modern laptops get quite hot when they're in use, and you don't want to set them directly on your skin.

You won't really need a KVM switch to attach your laptop to a monitor and keyboard, unless you want to continue using your existing desktop computer. (Which you might or might not want to do depending on how much you like the laptop you get.)

One big thing: buy two external hard drives. Yes, two. Use one for manual backups; make folders on it by date, and copy your important documents, photos, music, whatever onto it, inside that folder. This is like your historical record and makes sure that if you delete something accidentally, you can go back and get it.

On the *other* drive, periodically clone your entire laptop's entire hard drive over. There are tools to do this both for Mac and Windows. You should get in the habit of doing it every week or so, if not more frequently (like every time you plug your laptop in). This is so, in case your laptop gets stolen or dropped into the cauldron of Mt Doom, you can simply re-clone your drive onto a new laptop and keep working. Both types of backups protect against specific types of problems and you really need both, not just one or the other. With hard drives as cheap as they are, there's very little excuse not to do it right.

well, I did plan to keep my old computer, since it has a lot more hard drive space- 750 gb compared to 160, and I have software on there that would fill this hard drive in seconds (not to mention media).

But, ironically enough, the power supply in my old system departed this mortal coil last night. (there's a spare in the house, so it's demise may be short lived).