Hi there!
First of all, sorry for my poor English! 
I read the other two posts about Bloodhound.Boot, however they don't say if it is in fact a virus.
Got the alert when left clicking in Populate.
( My Computer > Properties > Hardware > Device Manager > Disk Drives > right click on Maxtor STM3320620AS > Properties > Volumes > Populate = Alert)
NIS2009 show this in History:
Component: Auto-Protect
Definitions Version: 2009.03.05.002
Risk Name: Bloodhound.Boot
Risk Category: Heuristic Virus
Risk Type: Boot Record
Risk Level: High
Risk State: Fully removed
Risk Items: Drive\Device\HarddiskVolume2
Quarentine is empty.
Running Windows XP SP3 Home Edition, NIS2009, all updates/patches.
Heuristics on Aggressive.
Computer is a Dell Dimension 5150.
When I change the heuristics to Automatic the alert does not occur.
Ran a Full Scan in normal and safe mode, all clean. Scanned with Spybot and CCleaner also nothing.
Nothing unusual in msconfig tabs either.
The system seems to be stable so far.
Is this a threat? Am I at risk?
Thank you.