^Knows what he's talking about (lol)
Dell's service is pretty good, and laptops without integrated GPUs are *very* rare. I've repaired about 6 laptops a day for almost two months now, and I've only worked on two which doesn't have an integrated video card.
IBM laptops are no longer in production either. A Chinese company called 'Lenovo' bought IBM's Thinkpad brand of laptops. A shame, really, cause the IBM logo is really cool.
In laptops, I would definitely go for Intel, as they have a better developed mobile platform than AMD. Though, I would probably go for Intel in desktops too now in these Core 2 days.
Also: Also, refurbishing of computer parts is done by all manufacturers. Every other motherboard I change has been used before.
Anyway...
1. I think any Core 2 Duo will be sufficient for you, to be honest :p. Any Geforce 7xxx or 8xxx (these are still integrated!) will most likely be sufficient for your needs too, unless you like to play all the newest games on highest quality settings. In which case, you want a new desktop computer, not laptop :p.* A decent processor and video card, nothing way over-the-top is necessary
* A battery that lasts a decent amount of time
* Windows XP
* A fairly large hard drive
* Wireless capabilities
* Oh, and one that can play DVDs too. I don't know if that's standard issue nowadays or not. x_x
2. Look for something with at least 4000 mAh of power capacity (Asking about this will probably melt the brain of the sales clerk). Maybe even 6000, but that'll probably be a bit costy. As Face said, a smaller screen will help battery life, because the screen uses a huge amount of power alone. When I close my lid and use an external monitor while on batteries. That's just for an example of how much power the monitor uses though, I don't expect you to get a laptop and carry an external monitor with you :p.
3. Few laptops are shipped with XP these days. Download your own WinXP Pro Corporate edition and install it. You're likely to be able to find the drivers you need. Failing that, just go with Vista, but turn off all the new features. It'll look the same and probably be a little bit more efficient.
4. 160GB or more will do. If you need more, get an external drive. That said, I just ordered a 250GB internal drive for my 3 year old laptop xD, but then again, i only have 60 GB in it.
5. This is standard, you'll have to go out of your way to find one that doesn't have it.
6. See 5.
Other things to note would be to get a laptop's that got 2 GBs of RAM or more, just cause RAM is incredibly cheap these days. Also look for one with eSATA for a future external drive, because it's much faster than USB2. When it comes to that display again, be sure to check the actual max resolution of it. Most cheaper models have lower resolution displays to save production costs. 1280x800 is a typical low-end resolution on 15" laptops. My 3 year old laptop's got that, and they're still selling lots of laptops with that a low res. You might want to check for yourself if you think a higher resolution display is worth the few extra hundred bucks.
Furthermore, don't bother with a 7200rpm hard internal disk. The reason laptops usually use 5400 isn't just cause it's cheaper. but because it requires less power to operate too, meaning longer battery life.