Haven't read through all the posts, but by any chance have you checked your IRQ settings and tried configuring the devices in question to be on their own separate IRQ channels? Also, have you tried any internet optimizer tools that tweak the TCP/IP settings?
The sad thing is, you can't do much with dial up anyway. There's always going to be latency issues mixing old tech with new. I get a few seconds of delay sometimes just when I click on my secondary 1TB HDD, or a program on it if it's library isn't already cached because I'm using old SATA II mediocre speed drives on a W7 64 bit OS.
BTW, I have switched from IDE to AHCI on W7 before without re-installing the OS via using the reg tweaks, and I had no problems with it.
Love your avatar btw. LOL
Last edited by Frag Maniac; Nov 22, 2012 at 12:02 AM.