Hi MickinPlymouthUK, No, it is not that difficult, it can be time consuming depending on how much of your files you have backed up and the size of the hdd. I have Wipe Drive and it take about six hours to wipe my 200GB hdd, no problem, I get it started and go to bed, get up in the morning and it's ready to go. Reinstalling the OS takes about an hour, and then it's about reinstalling the drivers for your peripheral devices and reinstalling your programs and files. If you have your files backed up on another hdd, CD, or DVD this can go quickly, I hope you get the impression that I'm pushing backing up your files.
One thing I would suggest is to make a separate partition on the hdd to install the OS and its' updates and use the second partition for your other files. This way if you need to reinstall the OS you can reformat that partition and not have to worry about the rest of you files.
As I said previously, I like Wipe Drive, but it is not free, and as it turns out their free trial only will wipe 25% of the hdd, but I have heard about good results with Killdisk
If you have the installation CD with the product code, have wiped the hdd, have your backed up files and driver CDs you're ready to go. One last step, you will need to go into the BIOS and make you CD-ROM the first device in the boot order, this will allow you to boot from the CD that you will make of Killdisk and you OS CD.