Ubuntu Studio is my vote. Mandriva- also good
Why would you even advertise here?
That is the most stupidly placed gold selling ad I've ever seen.
And for a distro with all your favourite propitary codecs and flash installed from the go. My vote goes for Linux Mint 7.
Definitely Linux Mint. Ubuntu based and very easy to use. They pre-install a lot of codecs so you shouldn't need to go searching a lot.
If you are new to Linux Linux Mint also has a very user friendly interface.