Inspiron 1520 / ExpressCard / Vista

Hello all, I'm helping a friend troubleshoot a 2 month old Dell Inspiron 1520. It's running Windows Vista 32-bit Home Premium. I doubt many other specifications of this machine have anything to do with the problem, although you never know. Basically, I own a SIIG 2-Port eSATA ExpressCard as well as a Firewire 800 ExpressCard. On my Dell XPS M1710, I simply insert a card, and Windows Update finds the driver and everything is fine. After the card is detected, I can attach an eSATA drive and it pops up in Explorer immediately. Perhaps the first time, it detects a new volume or disk. At some point trying to give friend some large files, I had him insert the eSATA card. Windows found the driver, and it shows up in Device Manager just fine. However, when I attach an eSATA drive, nothing happens. No errors in Device Manager or anything. Weird. I've double checked and re-checked all driver versions and everything looks good. The chipset drivers for the 965GM are the latest found on Dell's website. The driver versions for the card is the same as I'm using on the M1710. Then, with the Firewire card, sometimes it populates in Device Manager, other times it has the yellow exclamation of death. Most recently, it shows up fine, but as soon as a drive is attached, the error icon comes back. Unplugging the drive returns the card to a no-error state. So, we concluded that something with the motherboard or ExpressCard slot was bad. Friend called Dell and a dispatched tech came today to replace the motherboard. After booting back up with the new board - SAME THING!!! I had him do a clean install of Vista on a spare hard drive I had. After installing Vista and chipset drivers, it still does the same thing. I've run out of ideas. Oh, and I have like 7 eSATA drives in different brands of enclosures and different ones don't do different things. It sounds like a chipset driver issue more than anything. This is part of the 965GM chipset right? Any info would help!