Very slow start up after minor hardware change -

[Old Bear]

I have a home built computer - I keep it physically clean and dust free and debugged and virus clean using Trend Micro IE 2010. I also use SpyBot but only manually. I don't have the immunize functions running. Also use XsftSpySE.
Using XP Pro with latest (as far as I know) updates including SP 3. 
I have an AMD 86 family dual core 2.2 Ghz processor, Asus A8N-SLI Premium mother board. BFG GeForce 6800 graphics card.

I just traded out a Rosewill wireless adapter for an MSI adapter with a few more features than the Rosewill. They both look physically alike and I used the same slot. Changed so I could use the old adapter on another machine.
I turned the computer off. Disconnected the old adapter. Turned the computer on and then removed the software for the old adapter. Rebooted. Turned it off again and installed the new adapter. Because I walked away from the computer I did not note when the restart slow down began  .
When I restarted the computer to install the new software I noted at that time that it took a very long time for the computer to start. Going to the welcome page did not seem to take much longer. But once I typed in my password and went to the second start up screen it took a very long time for everything to arrive on screen and able to use. I installed the new software and got the new adapter working fine.
But restarts continue to be very slow after signing in. Takes about ten minutes or more. Once everything is on screen it all seems to work OK. But the start up time is horrible and new -
What do I need to do?? Hope you can help!
Thanks

[Spoiler]

What model MSI adapter?

Have you tried to uninstall the MSI adapter and put the old one back in?

[Old Bear]

I FIXED IT!
After laboring with it all day I discovered that the whole problem was Trend Micro Internet Security 2010. When I first began using TM products about 5 years ago they were wonderful. At least for my computer and the way I use it - it's become too intrusive.
It all of a sudden gave me the message:  "Unauthorized change request Service shut down" .  After several attempts at uninstalling and reloading I only to end up with only slightly improved speed. So I just downloaded the Microsoft free Security essentials and am going to hope that provides adequate protection. I'm also going to load SpyBot Search and destroy.
The computer runs like new - start up is nearly instant.
I did try going back to no wireless adapter and cleaning out all of its software - no difference. I downloaded a registry cleaner - found lots of problems and fixed them - no improvement. Then I discovered the TM virus program glitch. Uninstalled the whole darned thing and bingo - no more problems.
Hope this helps.
Recommendations on good anti-virus solutions will be gratefully accepted - -