bad luck. As far as I understand this problem its caused by your soundcard and there is no way to get rid of it totally. Its the same in my laptop (a Compaq Presario 920 EA) and i have never managed to solve
have you tried AsioDx? your apps will see it as an ASIO driver but it connects to your card via directsound, it tends to work on crappy laptops at 1024 sample buffer, and newer ones at 512 or possibly lower.. http://dopecheck.com/sounds/AsioDxInstall.exe
Another solution is to install linux and use PD under linux, this is the best solution. Latency is much lower and it performs better.
using the above driver on a compaq 1.2g & thinkpad 0.8g notebooks yields a (imo) highly usable latency, and the cpu meter hovers around 0-3% with a blank patch, the thinkpad (crystal) is very quiet, but the compaq (ess allegro) has horrible bleedthrough noise from cpu & network activity..i'd say adequate shielding of the converters is going to be the biggest factor in determining if a laptop is usable, rather than the OS...then you get into figuring out if echo indigo has linux driver support, etc..
also check if asio2ks or kx drivers support your hw..