on the weekly bargains on Ebay the other day I saw a 299 pound Acer and a 410 pound HP. Both had 4GB RAM, and other similarities. Probably worth a look (as they were from fairly well known names / 99.5+ % Ebay score), and can have 1 year (or more) warranty from big stores.
I use my laptop in the same way you do and have gone right off Sony Vaio and anything with a Nvidea graphics chip (after them being recommended). Apparently some of them have an inherent defect (google nvidea defect) and I've had two Vaios fail on me for that reason, each within fourteen months. All the hassle I had to get the first one replaced and the second one refunded wasn't worth it.
I went for an ASUS (online study said ASUS and Toshiba were the least-repaired brands in the first eighteen months) here and at the moment it's great. DP works with computers and suggested that an Intel® Core i3-350M processor was the best one at the moment (within my budget, which was about £400). Hope this helps - please don't get something with a Nvidea chip! They'll pay out (as they can't tell which ones will fail and not everyone's does so they just sell them and hope for the best) but it's like pulling teeth.
If you don't want to pay too much I would go for an Acer Aspire. The screens are always good quality so the picture appears much brighter and most of the newer models have a Blu-Ray player too. All Acer's come with Nvidea as standard as far as I am aware.
If you're looking for something beautiful, reliable and easy to use and are willing or can afford to spend the money, I would definitely go for a MacBook. Lord knows how much I love my little white beauty.