You might try going into "setup" when you boot your machine, and check how big the BIOS thinks yor hard drive is. BIOS does not care about how many partitions you have, if they are NTFS, FAT32 or whatever, or what OS you boot out of them.

Older machines may have a BIOS version that does not recognise a larger drive, 8.445Gb seems familiar, but I cannot remember the other "watersheds" off the top of my head.

Have you or one of the others run any of this fancy tweaking software recently? for example enabling DMA or whatever?

I have seen problems where an upgraded hard drive was put in a machine whose BIOS did not support it. The drive manufacturer provided a utility that loaded at startup and overode the BIOS (EZdrive I think). Somehow this got disabled, and the machine reverted to thinking it had an 8.445Gb drive

You do not say what file systems your partitions use, or what version of Windows you have....this may be a clue?

Hope this helps