Ijack :
I doubt that it's RAM! In answer to the original question you can have as many partitions as you might reasonably want (but if you want more than 4 on one hard disk then you'll have to make one of them an extended partition within which you create logical drives).
What do you mean "shows unallocated in Windows 7. I can't use that space"? Shows where? Are you saying that in Disk Management it shows as unallocated space but it won't allow you to create a partition using it? How many partitions do you already have?
I have the same issue... but close to 800Gb of wasted space. I right click on the partition and only "Properties" and "help" are selectable.
This is how I have it setup..
(All in NTFS)
1st Partition = 100Mb (Created at Win installation)
2nd Partition = 120Gb (Windows) - Primary
3rd Partition = 950Gb (Drive T) - Primary
4th Partition = 950Gb (Drive Z) - Extended
Then in disk management my last partition (5th) shows over 760Gb Unallocated space which is untouchable.