How to remove Vista from my laptop with dual boot

Hi,

I have an HP Compaq Presario laptop with dual boot - Vista and Windows 7.
My C: drive is becoming almost full. I do not know in which drive / partition these two OS's have been installed.

Now I want to remove/uninstall Vista os from my laptop and see if it frees up space in C: drive.

Please help me to remove Vista alone so that there is a straight single boot from Windows 7 next time onwards.

The following are the details about the hard disk:

DISK 0 Partition 1 (D:) Total 112.7gb Free:53gb Type:System
DISK 0 Partition 2 (C:) Total 16.8gb Free:1.8gb Type:Logical
DISK 0 Partition 3 (E:) Total 91.4gb Free:56.5 Type:Logicqal
DISK 0 Partition 4 (F:) Total 8.6gb Free:1.0gb Type:Primary [PREASRIO_RP]
DISK 0 Partition 5 (D:) Total 250mb Free:217mb Type:Primary