I can tell you from experience. Some of the smartest geeks I know seem to have an additional talent for music. Actually they might say they are musicians with a talent for PC's. In any case, here's a page of links from a musician I trust. Hopefully a fellow musician will someday benefit from this page.
Letter from Jimi
bro, almost every one of these links is freeware....a few MAY be shareware, but i doubt it...these are from my aol bookmarks, and are mostly VST (Virtual Studio Technology) plugins...there are also stand-alone programs including my fav audacity...
there's thousands of things out there, and these are from all over the world. one caveat: a spyware scan is a must after visiting a few of these sights...not because of the programs or plugins, but because ya run into nasties sometimes on the servers themselves..
anyways, hope these may prove helpful for some of your readers.