Not sure if this is the right place for this

This is a long story, I was on the net 1st April and computer froze so I rebooted and could not get IE or Firefox to display an page, I then pinged Google and all was fine,did a network dianostic and found 12152 error which related to the Zonealarm, disabled this and used the windows firewall and all seemed fine, until I switched users to the wife's account and nothing worked.Start button would not work, right click on folders showed no drop down menu and no processes in task manager.
Ran all the malware and spyware programmes I could thik off and removed everything
Ran AVG, Avast no virus found.
Did a windows repair no joy still the same( from the disk)
So have now reinstalled windows but it still seems not to be working well
Whist doing this recieved a strange phone call from someone saying they were from M/S support and asking me to purchase a software warrenty as my XP was old and I had been experiencing trouble
I have never heard of theis before so contacted M/S and was told this was bogus
Now we get to my question Iam feeling very unsecure at the moment and have decided to wipe my hard drive completely and reistall windows again
will this now make sure there is nothing on the clean install and I don't have somebody snooping around my system
Dave

 

Thanks for your reply, I,m still wordering where the phone call came from as I don't keep any personal stuff like that phone numbers bank detail's etc on the computer
It was paranioa over keyloggers etc that might have picked up my number when charging around on the web in a panic looking for a resolution to my problem
I have promised the wife I will scan every thing that is dowlnloaded in future and will be saving all download to a seperate drive berfore putting them into use
spo thanks again Dave

 

I used a programe called write/copy to wipe the hard drive using 8 passes(took ages)
then used G-Parted to format, then intsalled windows from my slipstrean disc It's all fine now have also got a patition on my second hard drive now, which I am using to backup my main hard drive once a week using Paragon drive backup, all downloads are saved in another partition to enable virus scan before they are put onto the system,and before I play with anything I now set a system restore.
Any advice on anything else I should do would be appreciated as I alway respect advice given by people who know more than myself
Thanks Dave (wanna be elderly geek 56yrs)