Wait. I would stick with the BCM 1000 box. If you are replacing the 1000 thinking that the 400 is more stable think again. I'm a die hard Nortel fan, but to be honest, I've become increasingly disallusioned with the BCM product. We have had a 50% failure rate of BCM Base Function Trays on the 400, and a 15% on the MSC card. Not nearly the same level of system failures of the old 1000's. I know, you're thinking that the 1000 has been discontinued for over 3 years, and it's old technology. But, every time Nortel tries to fix something on the 400 lately they seem to make it worse. The 400 is really unstable - and the crazy thing is, you think you're buying a redundant system, but any corruption of the main drive on the redundant system copies the corruption over to the back-up redundant drive. Kind of makes you wonder what's the point.
I'm just hoping that Nortel gets their act together and eventually fixes the 400 - makes a stable platform. Linux is just the OS and might make the software less buggy, but the core of the 400 cabinet remains the same.
Anyway, good luck with your upgrade - it will be a long night !