My current C drive is getting too full as a result of a partition. The HD is a total fo 10Gb but the C drive is is only 4Gb.

Do new HDs typically come with their own OS?

Is there an easy way to transfer all of the information onto the new HD?

Are there any tips ot tricks involved with installation or brand?

no you will have to install an OS on the new hard drive, you could keep the old hard drive as a second hard drive and move the contents over to the new one that way....thats the only way i can think of off hand, but i know theres more, but im just not thinking clearly today.

I use Norton Ghost. It creates an image of your current drive.
I partition my drive into 3 C, D, E. I put all programs on C (usually make it about 6GB) and then create an image of it on E(also 6GB). D drive is strictly for games, pics, vids and other misc. stuff(whatever free space is left on the drive).
This way if my OS ever crashes on me I just do reimage C with drive E, drive D is unaffected because it contains no system critical programs.
Make sense? :?

^ What he said ^

Can this ghost image be burnt onto a CD and copied to the new HD?

Absolutely. I usually keep an image CD just in case the HD toasts.