Illini,
We use the Norton 7.60 without issues. I'm assuming you have the latest release since you purchased it directly from Symantec. Here's the key to make it run pretty well:
1. Enable the File System Realtime Scans
This is scanning your drive in realtime, which means that if you receive an email with a virus in it, it will automatically pop a window up and notify you of the find. There is no need to perform manual scans of your drives, because they are very time consuming, hog all of the cpu time and become I/O bound by opening, reading, and closing every file on your drive.
2. Keep up-to-date virus definition files
This should be an automatic feature, easily downloaded from Symantec. This ensures that you have the latest definitions files that the realtime scans use to detect new viruses.
3. Try not to use scheduled scans.
These usually start at very inopportune moments and are very difficult to stop because of the cpu intensity and the I/O bind.
4. Correctly setup the options for when a virus is found
I have mine setup for when a virus is detected, it automatically attempts to clean the affected file. If not successful, it quarantines the file into a designated location on the drive, so that you can go in and attempt to fix it manually, and or remove the affected file.
I have multiple internet email accounts with tons of spam, so I get hit with viruses often. Symantec has never failed me. It's just a matter of not scanning your drive manually, let the realtime do the trick and that should alleviate 95% of your problems.
Z-