First of all, smash that downloaded, pirated copy of Windows. It's probably full of viruses and
backdoor trojans, plus you could get the boot from this forum for even suggesting you've done
such a thing. Oh, and there's always the possibility of going to jail.
Anyway, HP pc's have a Recovery Partition.
When you start your computer, press F10 to run Recovery.
This will completely wipe out all your personal data, but will restore your system to it's original state. (reinstalls Windows)
Do this fix but i would stress that what he did is not illegal in any way.
It is risky for his system because of as you say viruses, trojans and there is even a tiny slight possibility that the person that uploaded the OS is damn good at programming and reprogramed the kernal to either always put your hardware under strain but not show it, or to always send out corrupt stuff to possibly damage your hardware or give you a very unstable system, but that would be very hard and a tiny possibility,
Now i don't think i should go and say "it isn't illegal" without backing up my claim. So here goes, when you purchased your system you bought all the hardware, that is now yours, you also bought all of the software it came with, that is NOT yours.
You did not buy the software, you bought a liscence to use the software and if, like in the case of the OS, that software has multiple versions, you bought the liscence for that version and that version only, so lets say hypothetically that you had vista home premium on your system, you had the situation you now have so downloaded vista. It came with all of the versions and you thought i know, i'll do a quick upgrade here and put ultimate one, that would be illegal. If you put home premium on, that would be legal because you have a purchased liscence for that one version.
However that does not mean that you have bought the OS and now you can use it as many times as you like, you bought the single system vresion, not the multi-system key, so your liscence only covers you to use the OS you bought on one system, and one system only.
Alot of the stuff is common sense, but the main thing you must remember is that you didn't buy the programming or the features or anything, that comes into the price to pay for the disc it comes on, but the key is what you are paying £100+ for and so long as you have that and are using it for the purpose it was bought for (correct number of systems, correct version) it is legal to get it from (for example) a torrent and use that torrent, but if you do you are still running the risk of getting the virus' etc that have been mentioned above.
The best course you could take if you want a full reinstall is to find somebody you know you has a copy of the version of windows you have and install it using your product key. You can find the key on the bottom of the laptop, but again, for this to be legal it MUST be the version of XP that you purchased in the first place
