You can install over the top
Won't lose any settings or anything. It will just ask you for the keycode and install all the new files.

This is assuming you're installing the same version i.e. Home/Pro, SP1/2/3. Not quite sure how the service packs affect it.
(Potty Jag har smör i min rumpspringa, Tue 21 Jul 2009, 10:56, 2 replies, latest was 17 years ago)

it won't once it's registered,
it'll just download all the patches to get it to the latest version.

I hope he's got a fast internet connection.
(PsychoChomp, Tue 21 Jul 2009, 10:57, Reply)

Didn't know that
My previous experiance is from re-installing it using the same disc I originally installed from when a driver got corrupted and it refused to boot. Thats my new thing learnt for the day!
(Potty Jag har smör i min rumpspringa, Tue 21 Jul 2009, 11:13, Reply)

Take the oppurtunity
And start from scratch. Format, install from new. Its lovely when its all new, its fast and theres no shit. Makes me warm and fuzzy anyway.
( I have run out of coke is a little sweaty, Tue 21 Jul 2009, 11:11, Reply)

Agreed!
In fact I was forced into this recently! Marvellous.

Although I did lose some sentimental stuff. Must get me a cheap external HD for backing stuff up!
( whenanimalsattackhumans clad in global hypercolour, Tue 21 Jul 2009, 11:13, Reply)

You can buy 1TB drive in Tesco for £70 which I thought was flipping incredible

(Bazongaloid, Tue 21 Jul 2009, 11:16, Reply)

.
I would if I could!

Unfortunately there is a ton of stuff on there that isn't backed up, and it needs to be done today!
( Agnostic Antichrist Baltimora, Tue 21 Jul 2009, 11:27, Reply)