New To Mac. Need Help, newbie looking for info on used computer Options

i have many questions here. please bear with me.

i am a Windows user currently. i plan on, in the next few months, purchasing a Mac and getting rid of some of my music hardware. complete upgrade.

here is my plan: i am shopping around on ebay for a used Mac G4. hopefully 500Mhz. dual processors would be ideal, but more expensive. hard drive size not a big deal as i can upgrade/add new drives easily. memory, hmm... hoping for nothing lower than 256MB. 512MB would be nice, and more would be better.

what are opinions on operating systems? os 9? os X?
if the computer i buy has no system installed, how expensive/difficult will it be to install one?

is processor speed a big deal? what if i can only find 350Mhz? and what about memory? how expensive/easy is that to purchase and install?

and i just read a thread on hard drive speed. any comments on that? is it that important for music production?

once i get this computer, i plan on using MOTU Digital Performer with various plug-ins and left-over hardware. and then i wonder: what is VST? then i will need a sound card, which brings up another question:

where do i find info on sound cards? any suggestions? is usb the way to go? firewire? what is "audiowire"? can i get a card that is internal, so i don't have to mess with usb/firewire?

any info is appreciated. thanks for your patience.
semblance

[kaboombahchuck]

Questions after question! That's what we're here for
!

For your first comment on the duel prossesor, I think I would stay away form some of the earlier models, as they were quite buggy

As far as OS goes, I'm still stuck with 9....Going with X might prove hard to come up with all the programs you may want at first, but every one is swearing that X is the bomb.., Installing OS in macs is a snap! Goes right in. Thats the beuty of a system propriatay setup.

I'm not shure what to say about prossor speeds.... I'n running 350 mHz,,, Takes a bit when mixing tracks together, but other than that I Don't see the need to spend the money on bigger and faster at this time..... Memory on a mac is usually pretty much the same as PC (installation, type, and price).

Hard drive speed holds the same foe mac or PC The faster the speed the more tracks you can simaltainiously run.....56Krpm is somewhere around 12 tracks (or mabe thats on external hardrives, any way it would be 24 tracks max, if I am mistaken),.

I have not messed around with much motu stuff....And as far as sound cards go...I'm drawing a blank right now....If you have to go with external audio stuff audio fire wire is the only way to fly,,, I'm not sure if there are a whole lot of firewire interfaces for midi, but usb seems to work ok.