kaled - 7:01 pm on Feb 16, 2009 (gmt 0)

I can still work, but I keep getting I/O messages and things that used to take a few seconds are taking a lot longer

What sort of I/O messages? If software utilities are not detecting errors, it sounds like the disk hardware is fine and simply replacing the hard disk would have no useful effect.

Error checking utilities typically work at a lowish-level, whereas applications access files at a highish-level i.e. using caches and buffers, etc. to speed things up. These errors might result from faulty software (caching and buffering) faulty memory or even a faulty motherboard.

Kaled.