I've used Spybot since about 2000, and have always been very pleased.
I installed S&D beta 4 a couple weeks ago, and it looks and works pretty good.
My suggestion is to enable exclusions for the .exe scans on execution in TeaTimer. Part is for 'user friendliness', as the persistent scanning windows are very 'Vista-ish'; but also the scans seem to disrupt Office 2007.
The specific Office 2007 behavior is that when a office file (.docx, .xlsx, etc) is activated, the appropriate application launches, but errors and fails to load the selected file. Also, when using the 'New Microsoft Office Document' helper to launch a blank Office file, the 'Default' template for the selected app fails to open.
I've experienced the issue with Word and Excel.
My rig is a Sager np8750, intel i7, 4GB RAM, Windows 7 x64 (no service pack), AVG 2012, Office 2007.
The TeaTimer executable scan pops up consistently for AVG and system files - which tells me it's doing what it's supposed to , but is pretty distracting and gets annoying. It can be worrisome when in full-screen mode with the audio alerts sounding off every so often...
Thanks for all your hard work! You and S&D are greatly appreciated!!