From: United Kingdom
I have a vague recollection of something like 4 activations in 120 days, will result in you having to explain yourself to MS to get another.
There is a bit of a "hacker trick" that works with WPA.DBL - if you understand how the 10 items are counted - since ADDING an item that was not activated, is no chnge, while removing or replacing one is.
Declaring the system to be dockable, grants you a couple of extra changes (to account for dockable items).
Having the SAME Ethernet card MAC (not sure if "locally assigned address" counts) grants you 2 more changes, while having a different one cost you one of the existing changes.
Optical drives count, so maybe better to copy the install to HD, then disconnect the optical drives, remove a SCSI card if it's only there for peripheral support, and if you don't want to tie it strongly to the same ethernet card (unless it's onboard!), remove that, use a modem.
Basically, if you strip it down and tweak, you can make an activation which is very hard (but not impossible) to lose - given the growing amount of licence checking in Windows update, it's unlikely to be useful for piracy, but a smartly set up initial activation will give you an almost free hand in changing anything.
By the same token, if you were GOING to upgrade to a 10/100 Ethernet card, do it FIRST - you do not want temporary parts included in your activation, as that will just waste changes for nothing.