Very Slow Internet connection

I have two laptops running Win7 Home Premium 64 bit. One laptop gets normal internet connections - both wireless & wired; the other is very slow. I have updated all network drivers on the problem laptop. (Actually, when I automatically updated the network drivers from Device Manager the drivers were indicated as up to date.)

I did a complete scan with McAfee - 0 issues.

When I booted in Safe Mode with networking, the internet connection is normal.

I have looked at the startup and processes in MSCONFIG. There is nothing suspicious - i.e. the only software is from manufacturers that I would expect based on the applications installed.

What should I do to troubleshoot this problem?

Wireless adapter = Intel WiFi Link 1000 BGN
Network card = Realtek PCIe GBE Family Controller
Problem Laptop = Dell XPS L501X 4GB Memory
Win7 Home Premium 64-bit - SP1

Rather than trying to figure out what was degrading the internet connection - both wired & wireless - I restored the laptop to a date before I encountered the performance problems. The internet connection performs OK at that point.

I am now selectively applying updates and checking the internet connection performance before moving on the the next update(s). Hopefully, I'll be able to isolate the update that introduced the problem.