Any laptop you buy from any high street store today will be wifi enabled, so it will connect wirelessly, and have at least two USB ports so a mouse can be plugged in.
What does she want to do with the laptop? If it is just for internet, word processing, playing cds and dvds a �400 laptop will be more than adequate.
If she is a graphic designer, video editor or plays very high tec games, she will need a laptop with higher spec.
She needs to consider size. If it is going to be used mainly on a desk without being carried around too often - a large screen will be fine. Mine is 15.4" and plenty big enough.
If she wants to carry it around a lot, a smaller lighter one will be better.
If she is doing any sort of high spec design, then the biggest you can find would be good.
In my opinion this is an excellent buy:
http://direct.tesco.com/q/R.200-5446.aspx