Funny, I'm back!!!
My problem is that, because I use my machine SO much in my life, a problem grows [albeit in my head] so quickly... and I get impatient for a solution.
The guy who's "repaired" it says that there was near on 20 trojans inside the machine which he's removed. He also detailed that his scans indicated that the hard drive itself has some errors. The guy also informed me that Windows is on just Service Pack 1, so suggested that I update...
I've gotten home, plugged everything back in, and whilst the speed is back, it still gives that 'dark chirp' every 10 seconds (which I actually assume could be the hard drive issue?). Furthermore, IE8 and Firefox will not allow me to visit any antivirus sites such as avast.com; nor, connected to above will it allow me to visit any windows update pages.
The guy has offered for me to take it back to him, and he'll update to service pack 2 or 3, but he's away for a week... (as am I from Monday!)