Congrats on making the logical switch
It looks like the main things you want are HDD management, Security, and a few mac-like visual enhancements.
I would suggest getting CCleaner and Defraggler (both by Piriform) for the HDD management, which will replace Drive Genious 3 and Clean My Mac.
http/www.piriform.com/defraggler
http
/www.piriform.com/ccleaner
For the Mac Dock, RocketDock is made to emulate the Mac Dock.
http/rocketdock.com/download
For iStat Pro, I would suggest Speccy (also from Piriform)
http/www.piriform.com/speccy
For Little Snitch, a good router with built in firewall in combination with the Windows firewall should suffice unless you are into serious hacking and whatnot. In which case, I would recommend a UNIX based OS, but that's just me
As far as Quicksilver goes, you may want to try SlickRun. I've never used it, but I hear it's the best windows alternative to Quicksilver.
http
/www.bayden.com/SlickRun/
Also, did I mention that all of these softwares are free?
Welcome to the world of not being a mac