Personally got an acer myself and have to admit it has been a pleasure to own. Option A would be better, even with a slower processor the extra ram bringing you to 512 the recommended specs for windows xp means that you will get more from it than a faster processor and half that amount of ram. Do remember however the travel mate range are acers business laptops look at the aspire range (their home range of laptops) also will give laptops direct a big thumbs up as mine came from them and was 60quid cheaper than ebuyer offered the same unit for and I was able to collect it and test it in the shop and seak advice on it.
If you want suggestions give us a budget and we will happily suggest systems to you. I guess 400quid is yours or there abouts and you are not expecting gaming power but staples has a decent enough range on offer and they had an IBM t50e iirc for 399 on a few months ago which was a steal at the time and it works great, my sister has one and loves it. Add to that IBMs are more valued when it comes to reselling them as they are a trusted and respected brand so do consider what you will do when you upgrade as like buying a car it may prove worth it to get something different purely based upon what your return will be from it.