I use Acronis Disk Director Suite 10 when I need drive partition management. In Vista it's a bit harder than with XP, as Vista wants about 10x more space made available than what is used. It's quite annoying to resize on the fly, but Disk Director makes understanding what partitions to what drives are, diagnostics, changing drive letters, and hiding partitions, and can even clone a partition from one to the other. It does a lot more, click the link to see more.

XPS 630i Intel Core² (Wolfdale) 3.0 GHz; BIOS: 1.0.13; 4 GB DDR2 @ 800 MHz;
Hard Drives: 320 GB, NCQ Western Digital; 640 GB, Seagate;
Optical Drives: 48x Combo CD-RW; 16x DVD+/-RW; Creative X-Fi PCI Sound;
Nvidia GeForce 9800 GT w/ 512 MB; 19 in 1 Media Reader w/ Bluetooth;
Vista Home Premium 64 Bit, 32 Bit; Windows 7; 2.4/5 GHz Wireless 1505 PCIe WLAN