Win XP Install And Serial Key Question

I'm getting ready to purchase a new machine and load XP onto it, but have 2 questions about the install of XP (for 2 different situations):

1) Is there ever a case where a particular serial key is tied to the CD from which it came? In other words, say I purchased Win XP originally when it first came out in 2001, however I lost that original disk. Could I borrow a disk from a friend who purchased it recently in last few months and use that same key that I have from 2001? Do the new builds/service packs come into play at all here?

2) Also, say I purchased a machine from Dell with XP installed. Can I use a Windows XP disk not acquired from Dell to reload Windows on that machine using the key I got from Dell?

1. The XP CD must match the Product Key. ie: Windows XP Pro OEM CD must have a Windows XP Pro OEM Product Key.

2. Yes, but you'll have to call MS to activate and again the CD and Product Key types must match.

Grumpy

The key must match the version of the cd that your using. If you purchase an OEM copy of xp you must use an OEM product key. A corpoerate version cd will need a corporate product key and a single user license will need a single user key.
The cd key is not tied directly to that disk, just the version/kind of disk that the key will work with.