|I disagree with the above comments about partition size. 100GB is more than enough space for the OS partition.|
I doubt that has anything to do with the issue you are now having.
Did you install the motherboard chipset drivers? Watch the POST screens to verify your hard drive is being properly identified by both the model number and the FULL drive capacity.
Check Device manager to see if all if well there. Expand the IDE ATA/ATAPI adapters and right click on the first IDE listing. Choose properties> advanced settings. Is DMA in use? Repeat for any other IDE channels.
If the hard drive is SATA then look at the SATA controllers. There is a speed test you can run. Could also be listed as IDE 2.3, or more.