I recently replaced the family laptop and decided to load up CentOS on the old machine. Old is relative - it's about 5 years old. Anyway, having two Linux laptops in the house will allow me to play around with DHCP, DNS, NFS and some other services before I make the plunge into certification.
2.0GHz processor, 2GB RAM and an 80GB HDD.
The install took 3.5 hours for a vanilla install.
Pretty sure the hard drive is on the south end of its lifetime. Dropped in a replacement, and it's installing now. I expect it to take maybe 45-60 minutes (IDE HDD, not SATA). It's already moving a lot faster.