Lowest possible latency with notebook and external audio interface?

Running Pianoteq 3.02 stand-alone on a Dell E6400 (Core 2 Duo, 2.5Ghz, IDT HD Audio sound chip, ASIO4All 2.9), I cannot get latency down to less than 8ms (352 samples) before crackles start to appear on heavy load.

I used to have a Dell D800 with a Sound Blaster Audigy 2 ZS Notebook card and - as far as I remember - this had no problems running Pianoteq 2.3 with 3ms (128 samples) latency. Sadly, this card is PCMCIA and the version of the Dell E6400 I have only takes ExpressCards.

The few ExpressCard-based sound cards seem to have little or no ASIO support.

Questions:

1. Has anyone with IDT HD Audio been able to obtain lower latency. If so, what might I be doing wrong?

2. Would it be possible to obtain lower latency (than 8ms) with an external audio interface? I presume this would have to be Firewire rather than USB(?) This is a rather general question, I know, but when reading audio interface reviews, the focus is usually on either 1) big configurations with dozens of vst(i) instruments and effects or 2) direct-monitoring when recording. None of these scenarios tell me anything about latency when playing a single instrument live, so since the topic of interest is Pianoteq, would anyone care to share what latencies they are able to obtain with which specific Firewire or USB audio interfaces?

And to those who say 8ms is just fine: I can feel the difference in latency when switching from Pianoteq to the internal sounds of my Roland RD700SX. The difference was not as pronounced when I used the old notebook with the PCMCIA card.

Thanks,

Joergen Bech