I agree with dr/owned on all counts: Although on the surface they are "similar" models, yes, the drivers will be different.
At the same time, the new notebook you are looking at appears a good replacement, and although nothing is a "lock", you should be able to wrangle XP drivers for it.
I will say this: IMHO, it makes little sense to buy notebooks (or desktops) with an OS that you do not plan on using. There are notebooks out there (though the number is shrinking!) that can come pre-configured with XP, and if you want a "guaranteed" seamless transition, well, then get one with XP!
I must say however, and don't get me wrong, I do not "knock" people's preferences, but why XP Pro? It is after all a discontinued OS, which will only get more difficult to match up programs/hardware with in the future?
Were you a "gamer", from a performance point of view I might see it, but with either your old, or proposed new notebook...neither of these are gaming rigs with integrated graphics, right?
Outside of a relatively small handful of older software, most software runs just fine with Vista, and you are ensuring future compatibility (at least for a longer period of time). Most of the early angst with Vista has been largely corrected, both by MS updates, but also hardware/software manufacturers making their adjustments as well. Why saddle a new computer, with an outdated OS?