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#11
I would ditch Norton as it can be trouble. Stick with MSE and Win7 firewall kept automatic Updated.
The MSE listing in msconfig>Startup will be under MS. Put the cursor on each line of each listing until it reveals the program. Make sure it stays in the System Tray.
Win7's native instantaneous performance relies upon having a perfect install on adequate hardware. Compare the install you have with Clean Reinstall - Factory OEM Windows 7. I would at least Clean Up Factory Bloatware until you get a perfect reinstall.
If in doubt about your hardware run the Windows 7 Upgrade Advisor and the hardware tests in troubleshooting tutorial.
You can also gain back some performance using Optimize Windows 7 - Windows 7 Forums especially editing Visual Effects of animation, sliding, fading, dragging intact and selection rectangle. These are huge resource hogs.