Old core duo iMac 17" which hd for upgrade

Just got away from Windows at last.
I got myself a case damaged 17" Imac with 1.83 core duo cpu. for £300 from ebay
was able to repair it but the hard drive is only 150gb
I know its sata but is there any hardware or os limits as to the size of the harddrive i can install.

My Emac 700mhz has a 160gb in it lol....
I am running lastest OS which came with it 10.5.3 i do have restore cd so thats not a problem.
looking for at least a 500gb as I will be getting more it video editing hopefully soon

Cheers

there are no limits to the size of the hard drive

Thanks for that. at least the cost of hard drives are still low.