Your machine should boot quickly and run even more quickly. I guarantee that w/o a package to protect from spy-ware and viruses your machine was infected on day 1 and only continued to get worse since.
Ad-Aware et all are OK, but this stuff is too critical to cheap out on.
I highly recommend a subscription to Webroot's "Spy Sweeper" it is worth it
If you don't have A/V get that too, I agree Norton suc**