cor, quite a lot of stuff to answer here...
First off, it's not a valuable computer - I picked it out of someone's rubbish! I asked and they said it didn't work, but all it needed was a fresh install of windows and a bit of work finding the drivers. I can also get another for nothing from a friend who works for a hospital which is gradually replacing all its computers and binning what's left!
It is, I think only just fast enough for this project, but all it has to do is playback video files and run iTunes (not at the same time tho). It's going to have to have windoze on it, by the way, as nothing quite touches iTunes, as far as I'm concerned.
The oil is for cooling - esp of the cpu. I only found out when I took the case off, but the cpu fan was already dead, and it's not fried yet! I was planning on sticking a bigger heat sink on it, and then relying on the oil to dissipate the heat. BTW, the video card doesn't have a fan anyway. As cwiz said, I'll just check up on the temp during normal running, and if it still needs cooling I'll figure something out then...
I don't mind the HDD and DVD drives making a bit of noise - they'll only spin up when they're in use, so they'll be drowned out by the music/video. I just want to be able to leave the thing switched on without having a constant whirring.
I also didn't want a vanilla PC case skanking up my sitting room, so I'm converting a nice looking wooden drawer from a broken sideboard into a case. I have some perspex spare, and some sealant for the edges, so I'll make a perspex box that sits inside the drawer and put the mobo in that.
It's all costing very, very little. Which is good, because I'm skint! I can't afford to buy any clever silencing components at the moment, so I just thought I'd see what I can make with the resources I've already got!