Why Does It Take Me So Long To Install Windows 7

I find it weird that when I install Windows 7 on my computer it take a good 5 hours to install. But on the other hand I also tried to install Windows 7 on my Toshiba L305D Laptop, and it installed in 30 minutes. The weird thing is that my computer is way faster than my laptop.

My Computer Specs:

Intel Pentium D 3.20 GHZ
4 GB RAM
500GB Samsung SCSI Harddrive
SAMSUNG Black 22X DVD+R 8X DVD+RW 16X DVD+R DL 22X DVD-R 6X DVD-RW 12X DVD-RAM 16X DVD-ROM 48X CD-R 32X CD-RW 48X CD-ROM 2MB Cache IDE 22X DVD±R DVD Burner

Laptop Specs:
Athlon 64 X2 Dual-Core
3 GB RAM
250 GB - Serial ATA-150 Harddrive
DVD±RW (±R DL) / DVD-RAM - integrated
Read Speed: 24x (CD) / 8x (DVD)
Write Speed: 24x (CD) / 8x (DVD±R) / 6x (DVD±R DL)

The only operating system that installs on both at the same speed, is Windows XP which installs in like less than 15 minutes.