http://forum.doom9.org/
is the doom 9 forums, and
http://forum.doom9.org/
for the main site that is more general news etc.
this site is filled with people with a broad range of experience to draw upon.
to get into things at a cheap level go to http://www.virtualdub.org/ and download virtualdub. this is a free god value editing tool and for most people here, the base program of choice for a lot of basic editing such as splitting files, recompressing, color correction etc.
when used in conjunction with www.avisynth.org which is a site that deals with a scripting language where you can use additional filters in conjunction with virtual dub. virtualdub, or vdub as it is more commonly referred to also does video capture so as I said, it's a good cheap way of getting into the hobby.
from the audio side of things, soundforge isn't bad but expensive, Sony vegas 5.0 is a capture program, linear editor, and sound mixing suite and very very good. there were some older threads that dealt with how to make 5.1 sound out of stereo tracks on this board and doom9 goes into this in a great deal of detail.
besweet is a good program to convert wav's to mp3 or ac3 digital files. there's a lot more I could say but the best thing to do to get started is to get virtualdub, look into avisynth and all the additional filters you can download and read on doom9 forums and just start playing. you learn a lot just by doing and if you need advice, the guys on the board at doom9, videohelp.com or here can help you out if you have issues.