Latency Monitor software.

[senso]

You probably know the soft LatencyChecker which measures the realtime capabilities of your computer, in other word the latency of your sound card.
http://www.thesycon.de/deu/latency_check.shtml

But I fond a more interesting soft called LatencyMonitor witch also measures the latency but can give the name of the responsible driver. For advanced user only ...

http://www.resplendence.com/latencymon_using