Using grub command line

Recently, I installed CentOS 5.5 from hard disk with an existing Windows 7. 
During my daily operation, I accidently damaged CentOS. So I need to reinstall
CentOS. But my desktop does have a CD-ROM driver. Ant it does not support USB
boot. So I need to hard disk installation for CentOS. Unfornately, the grub menu
does not show Windows 7 during booting. So I manually boot Windows 7 with grup. 
Here is how I have done it. Type c when the grub menu shows up. The time
count-down stops, type c again. The grub command line shows up. Type the
following grup commands:

rootnoverify (hd0,0)
chainloader +1
boot

After done it, Windows 7 will boot. Note there is no space in (hd0,0). 
Otherwise, device string errors will show up.