My brother is looking for a relatively inexpensive MTB and has narrowed it down to these 2:

06 K2 Attack 1.0 full-suspension ($600)

vs

05 Specialized Hardrock Pro Disc ($650)

Both seem to be good starter bikes that have some upgradability... and he likes them both equally it seems.
Components seem a little better on the HR - but the FS of the K2 is nice.

Any opinions are greatly appreciated!

Thanks in advance!