When it comes to computers, I'm not all that clued up so please be patient... My home computer is running Windows XP Home Edition. It has been updated with all the updates and service packs and has been running Ok for about 5 years but has gradually been getting slower and slower and now some usually reliable applications (GSAK and MemoryMap to name but two) are starting to show problems. I would like to 'clean it out' and start again. I've been given a new and unused copy of Windows XP Professional Edition. The package is still sealed and it has all the hologram stickers and stuff and looks perfectly genuine although it says that it should only be supplied with a new computer.
Question 1... If I just put the CD (DVD?) in the DVD drive, will it start up and install the new O/S without me having to un-install the current system first?
Question 2... Would it be better to reformat the hard drive first?
Question 3... If I do reformat the hard drive, will I lose the drivers for the DVD drive and end up not being able to read the new disk?

Thanks for any help offered and if I've missed the plot completely, please don't laugh
John