Unallocated space

[fsexp]

Hi,
I would like to know the duration to enlarge a partition on a server.
HP DL 380 G4, bi-xeon 3,4Ghz, 4Go RAM, Win2k3 SP2, RAID 5 HP.

first partition (system and Data)
size max: 840Go,
used space: 629 Go
free space: 211 Go (25%)

Second partition (unallocated):
size max: 560 Go

thanks