I can find no documentation listing a maximum array size for the ICH7R chipset.
That would be 2TB until you get to ICH9R or higher allowing 2-256TB data volume support.
Where did you find this info?
You can create 2x2047MB RAID 5 arrays and you'll have 97.7GB left unused additionally.
I ultimately did find the table of max array sizes on Intel's website, and PeterUK is correct about the 2TB limit on an ICH7R. I bought a new motherboard with an ICH10R (aka Series 4) chipset, and I was able to create the 4.5TB array. Note that I also had to install a 64-bit version of Windows, since 32-bit versions have a 2TB per disk limit.
Hopefully Google will index this entry so others can find it.