Laptop - HDD upgrade, or new laptop

I have a nice Sony Vaio laptop, which is getting a bit long in the tooth. It is the VGN-FS790P, http://www0.epinions.com/reviews/Son...01_PC_Notebook

It is still a nice laptop, with a good screen, and a nice keyboard, it is light, and I personally think it is plenty powerful enough for basic use - internet, docs, etc. but it has been quite slow recently, and I think it is in need of an OS reinstall.

I've already been looking at buying the new Windows 7 Family Pack with 3 licences for £113, which would allow me to upgrade my home PC and this laptop, and sell the other to family/friend for the remaining 3rd.

Then I was thinking, the biggest problem is actually the hardisk - so maybe I could just upgrade to one of these new combo SSD-Platter hard drives. The original hard disk was 80GB or along those lines, so a larger disk wouldn't go astray. It is also only 5400rpm, so the speed increase should be good. They are around £80, right?

Last i need a long life battery, which is another £60
http://www.sony-laptop-batteries.co....-vgn-fs790.htm

So for under £200 I could totally rejuvinate my Sony laptop to something which boots faster, has a fresh OS and good battery life.

What is recommended for around this price to compete with this?

Anyone tried one of these new hard drives?

The only reason I can see to upgrade the entire thing is for extra new features, like Wifi .n and bluetooth (which i do use), but these can be solved with external dongles (bt dongles are cheap, wifi .n ones probably will get cheaper). But is there anything else I'm not thinking of?