First make sure that the laptop your getting is 64bit otherwise all that ram is wasted.
Second check the graphics card. Is it 1gb of on-board, dedicated or discrete? (On-board not so good as it uses your memory, dedicated has a gpu but none of it's own ram, and discrete is the best because it's a gpu with it's own ram.)
Third for Office at that price that will be the student price (all though you could consider open office, although it's not the be all or end all of word processing.)
Fourth, warranty. While myself will ALWAYS go for one, because after working retail I saw a crap lot of computers come back after the first year. However since this also has damage insurance, it means that if your laptop is accidentally damaged (i.e a non-warranty fault) you're not going to have to fork out for the repairs of the device. Read the fine print for the warranty first before you buy. Make sure what exactly it covers or doesn't cover. If you have home contents insurance which covers the laptop for non-warranty damage, it maybe cheaper to buy the hp extended warranty.
Finally laptop bags are handy. I like backpack type ones cos they're easier on my shoulders.
As for other things every laptop should have at least g wireless built in, and you'll have the usual ethernet port and usb ports. Depending on how many things you need plugged in at once, you may want a USB hub.