The only limit to modern HDD size was the 137GB limit but that based on your OS. XP before SP1 and 2000 and back had this but when XP SP1 came out this limit went away. If you use some of the HDD manufactures installation software you have to use the Advanced install tab instead of express to format the drive to it's full capacity. That is the only time that I have ran into a HDD barrier in the past 9 years that I have been building systems.
Should support any size drive. Although I have seen some people with older boards having issues with the new 1 terabyte drives, but I believe there are work arounds, check out the vendors website for compatability issues if you are wanting a drive this large.
The OS you are running is the main concern for the size of the drive.
Soooo.....what OS are you using?