Another review writer mentioned overlapping IRQs - which suggests they were out of the loop when the entire computer world changed to Level Triggered IRQs. In a nutshell, current systems are designed to share IRQs, this is a critical function for any system. If you have older PCI based cards or a computer older than 4 years this is when you can see problems, as they use what are called Edge Triggered IRQs and are not shareable.
Still, installing add-in cards to your PC is not for the faint of heart or the uninformed, even with the advances in Plug and Play technologies. Get your friendly neighborhood computer genius to help if you don't feel you're savvy enough.
That being said, this card from Adaptec works flawlessly, and has some nice features designed into it. The bus mastering PCI functions work reasonably well, unlike some lower priced cards that seem to cause more lock-ups and pauses. The addition of an internal Firewire and USB connections are a great help to case modders and others who build their own systems yet still want ports on the front side of their machine so they don't have to reach around the back. Having USB and Firewire on the same card is handy, since most older systems using USB 1.1 use a riser card that can be replaced easily with the Adaptec.
A good value for a complete high-speed hot pluggable I/O solution.

Excellent way to add USB 2.0 and Firewire to your set up. Works as advertised and, most importantly, it works flawlessly with the 2.6 series Linux kernel. Linux supports ohci, uhci, and ehci on the USB side and also supports firewire. Easy to install, too.

A convenient way to upgrade your computer to today's technology!

I was a bit nervous about buying this card after reading some of the reviews published here on Amazon, but I did anyway--I wanted to upgrade my computer's USB jacks, and I wanted firewire for the convenience of using that with my iPod.

At any rate, my fears went unrealized. Installation under Windows XP went without a hitch: the thing was ready to go five minutes after I opened the box. I can't say I've tried it under different operating systems, but under XP, it's a dream.

Easy to install and the information it shows about your usb plug in is great.

I am running Windows 2K Pro. I bought the Adaptec AUA-3121 USB 2.0/1394 Combo Card. I openned the box. I read the instructions. I followed the instructions. Everything works perfectly. Went smooth as silk.
Also note that I have Belkin USB 4 port expander. Since installing/using the expander my Logitech Quick Cam has "complained" of insufficient bandwith. I have since moved it to one of the USB 2 ports on the Adaptec card. I now have a happy Logitech camera also.
I rate this card as first class. READ THE README file and installation instrcutions!