I've decided not to overclock now as I've had this 3700 (2.2GHz stock) sat at 2.7GHz for a while and the motherboards crapped out now, so I'll stick with stock unless the PC becomes stupidly slow.
And about the HDD, I'm not sure. I've had 3 x 300GB Maxtors in this PC since I bought it over 3 years ago and they have not skipped a heartbeat, yet the Samsung 80GB SATA II drive I bought less than 2 years ago has already gone to HDD heaven
So, Im more favourable of Maxtor HDD's as they have never ever let me down (and I've owned about 6 of them!).
Thanks for all the suggestions thus far, but at the moment cash is a problem so cheapest bang for buck is the best.
Anymore suggestions however are more than welcome!