I am not too sure on how the whole entire hard drive deals work, but even though the 4.5gb limit appears, i would not make a partition that is RIGHT on the barrier line, just to be safe..... I would make the partition 3.9gb or so in sizes. I am not sure how to go about if you want bigger partitions then 3.9gb really, but all I know is that OS 3.9 does the first paritition 4gigs, and the rest can be whatever sizes you want them to be.
Hope someone can help better then I can. :-)
