Hard Drive Space

Hi,
I just upgraded to SP2 and noticed Vista has given me back some more space which is good. The bug is that it still think the overall capacity is the original. It's hard to explain.

OK, so I bought the computer and the drive was 217GB right? From 250GB you don't need to explain to me why that is. And anyway, after the install, the capacity increased as SP2 has somehow managed to do this. So the grey text underneath says 141GB free of 217GB when it is actually 233GB. I know this because if I go to the properties it says 81GB used, 152GB free and capacity 233GB. Also, after the digits in bytes are, the overal round off is wrong:

81,707,792,432 bytes is rounded to 76GB (lol)
152,109,969,408 bytes is rounded to 141GB (lol also)

Those rounded figures add up to 217 but the actual figures do not.

Is there anyway I can get the estimate to match the figures or is it just a non-fixable bug?