I'm running osx 10.4.9, and my Ableton crashed so i'm using garageband (getting tired of radio effect haha). And every time I download a vst plug in, I can't figure out how to install the file. I'll get messages like "there's no default application to open this program", or safari can't open find specified target. Do I need winrar or a program like that to decompress?? Thanks for any help.

About which plug-ins are you talking about? What's the file type? Is it compressed?
Are the plug-ins legit? (sorry but piracy is a big no-no here)

Plug ins go in their relevant folder in library/audio/plug-ins/

Note that "component" is for Audio Units, the others are self explanatory.

btw winrar won't be of much use on the mac…

"win"rar, sometimes I don't put two and two together. The programs are .vst and .sit, and they aren't bootleg. One i'm tryint to get working is MJcompressor.vst . When you say they go in their relevant folder in library/audio/plugins i'm guessing thats what makes it open with garageband? I'll try looking for that folder and getting it in their while I wait for a reply. Thanks

No offense meant, just a strict policy around here.

.sit is a stuffit archive, have a go at Allume and download the free Stuffit expander

.vst is the plug-in in all its nude glory… And VSTs are going into the VST sub folder of the plug-ins folder (pretty neat uh?) If there's no VST sub-folder, create one, now…

Now it won't work anyway as VSTs are not supported by GB, you need a wrapper like FXpansion VST to AU. Another solution is to look after AU plug-ins which will work in GB.