Rick-
IMO (i don't know a lot about computers outside of recording) you should look for something with maximum RAM and at least 30GB of memory. You want something that is fast with plenty of room to store your recordings. You do not want to have to delete a show to make room. Also the smaller the better. I use a fujitsu lifebook....it is very small and has been very reliable.
As far as batteries go check out electrovaya power pads. They work with any laptop and are exceptional. I get 10 hours with the lid open of recording time with the 120. Electrovaya also makes a 160 that will give longer record times. Check for them on ebay..a bit pricey but worth every penny. Also make sure you get the right one (120A, 120B...ect) to go with your laptop.
One more thing to consider is your pre/ad. You will need something that will produce a 24/96 or 24/48 signal. This includes Mini-Me, UA5(cheapest) and the V3. With the V3 you will need to get something to go from coax to USB or better yet firewire.
Also you will need a recording program. I like Wavelab since it does a seemless split after you have recorded 2.0 gb of music.
I LOVE recording to laptop. It is super easy once you get the bugs worked out, and NO transfers. Just plug into your stereo or heaphones and add the trackmarks. Too easy.