Ok I am not new to Linux but I do have some questions that I'm sure a guru here can answer.

I need more harddrive space and I'm thinking about getting a huge harddrive (thinking about 300GB). Now I'm not sure about information on my motherboard because my system is older (I believe I got it in 2000), I'm not sure what model my motherboard is because I would have to essentially rip my entire box apart, and I don't like to restart. But the low down is I want to know if my motherboard will support this new harddrive (I haven't bought it yet so that I don't go and waste $100-$150).

Also if worse comes to worse would it be better to get an external case for it and use USB. Are there any size limitations with USB?

The next time you reboot watch the post to get at least the motherboard Manufacture and bios version. Without those you really will not know for "sure". Even if the motherboard does not support large drives you can add a card that does. These have been around long enough they should be cheap. You may want to consider a sata card and going with sata drives to "future proof" your investment. If you are running a ethernet network you may want to consider using a ethernet NAS device. Some of these have a built in ftp/smb server for around $100. Oh, I would consider 300gb to be "average" size these days. (750gb availble)

lazlow

Try installing lshw if it available it might be able to tell you the motherboard model.