My opinion - it don't matter much what label is on the outside, it'll be either AMD or Intel on the inside with little or no real difference between them. On video cards there is basically ATI (AMD now) and NVidia, so again, not a lot of difference. Oh, I guess you could mix Intel into the works, but that is if you are grabbing a machine that uses shared memory for it's graphics which will rob a nice sized portion of RAM from your use and turn it into video memory slowing your PC but making the graphics look a bit prettier). As you point out, 2GB is minimum, but then again in most laptop configs you may find that 2GB is the maximum you can do. You might consider that aspect when shopping and go for a laptop that can handle more than 2GB if possible. Perhaps 1GB built-in with ability to add 2GB in addition to that. At least that way you'd be able to break out past the 2GB mark if necessary.
With Vista, if you have a USB Flash type drive that supports ReadyBoost it'll help performance on any machine using 2GB or under. That would obviously include a machine that has 2GB but which has sacrificed some over to (shared) video memory. 512MB of ReadyBoost flash drive will help speed up disk access somewhat and return some performance back to you without you having to spend a ton of money on the flash drive. 2GB flash drives that support ready boost should be available at a fair price too. Only real disadvantage to using ReadyBoost is you pretty much sacrifice that USB flash drive to that task and don't want to remove it once you are running. Meaning you no longer have a USB flash drive to use for your own storage but instead you've sacrificed it to system needs.
If you spend up into that $1k range and just beyond, you may find a system that doesn't do the shared video memory and instead has a half-way decent built-in video subsystem. Only real problem with that is it'll get dated fast anyway. Laptops tend to lag behind desktop performance wise anyway, and the chipsets for video and such keep rapidly improving. Depending on how long you intend to use the system, you may find it gets old quickly.
If you don't mind a refurbished system, you can check TigerDirect.com. You may not like some of the brands they offer, but they do offer warranties on all of what they sell. Multiple brands with prices starting in the $400 range, working up as features increase.
NewEgg.com also a cheap place to check. Both being mail order typically means you aren't paying sales tax, but that may wind up a wash when you consider shipping (though TigerDirect.com often times has 'free shipping' sales that will help avoid that issue too).
You could also check Freecycle.org and/or CraigsList and eBay for used systems that are still expandable. I found a decent used system in another forum area I frequent. Person was going to sell it but couldn't find the O/S media. It helped keep the price down to a reasonable neighborhood for me to purchase, and now it's my wife's system to use wirelessly in our living room while my youngster monopolizes the family PC.
Best of luck with whatever you get. You have enough PC skills to survive pretty much anything so I'm sure you'll do just fine. Hopefully you can grab something at the lower end of the range and save some money now that can be used to get a better/faster system later if you really want.
