a lot, most now are done by programs but I did the reg hack before I found out about the program, the main one which is the most important one to me is the one where I can have a different background for each of my 4 monitors, the 2nd and also almost equally important one ... having a task-bar for each of the monitors ... both now are done by display fusion ... so if I do kill my win 7 install I can get that and not have to do the reg hacks. But outside of reg hacks I have completely re done the main libraries for the OS I have removed a lot of legacy crap libraries and then add the many different compilers so that my install can natively compile C++, C, Java, Perl, and many other languages ... this all being said my OS footprint is fucking huge ... around 50GB for just the install.
I have left the main controls and the way the OS works alone, I just made it easy for me to do my coding at home and not have switch between or waste my ram on a Linux VM.
But that does not mean that I dont use my linux partition
Different background on each monitor: It's already in there
Taskbar on each monitor: yep, it's there too
The coding thing: I'm not so sure...
For me, I think I would need a new hack to disable Windows Media Foundation, driver protection and hack the Bluetooth's "Play" button to open media files in defualt player (not in WMP). Then again, the only hack I found out of the three with Win7 was the WMF thing.