Theducks earlier advice about antivirus could help you in the meantime.
I can run calibre reasonably well on an old Dell inspiron 9300 laptop with lower specs than you have. takes less than 30 seconds to load 10000+ books and my HD is only 5300 rpm 60G. (I use Microsoft Security essentials which seems more than adequate and is less invasive than some antivirus software)
Of course a new machine would be must faster. My i7 desktop is much better
