If anybody wants to know how I get rid of this ...
My friend had some horrible stuttering when he switched to windows 7 as well. It was like his framerate or internet was lagging really bad, but his ping was low and he was getting 100+ fps constantly. Anyway, he found out that the MMCS service (Multi-Media Communications System) in windows 7 was the cause of it. Since -nosound fixes your stutter, it might be the case.
Here is what he did to fix it:
Edit: I forgot to mention that the fix for this problem is to Disable the Multimedia Class Scheduler service (start menu-> run-> services.msc-> right click, properties for MMCS service-> choose disable). However, this service is, by default, required for the windows audio service (meaning you'll have no sound without it) but you can change this by opening regedit, navigating to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\Audiosrv\DependOnService and removing Multimedia Class Scheduler Service from the list. Restart and you shouldn't have any (network) lag in TF2 under Windows 7.
And as always when messing with your registry, be careful.
SteamForum-LinkAfter that my FPS went down from 80 to 30-20, changing DX to 8.0 helped me to get the game playable again ^^"