Identify version and/or service pack level

How to identify your SQL Server version and edition
http://support.microsoft.com/kb/321185

Related
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Workaround for SQL 2000 Desktop edition database size limitation:
MSDE has a 2GB data file size limitation - but it only checks the file size when trying to GROW the data file.
You can restore a database created on Std Edition or Enterprise Edition that is ALREADY bigger than 2GB, and MSDE is OK with that. As long as you don’t run out of space in the data file (and MSDE doesn’t have to enlarge the file) you’ll be OK.
source: MSDE Database Limits

SQL 2000 Editions comparison:
Choosing the correct SQL Server 2000 edition

SQL 2000 edition that is free?
The downloadable version of 2000 is MSDE... Personal Edition is not free downloadable
source: Download SQL server 2000

MSDE 2000 Release A functionality is the same as MSDE 2000 SP3a
source: ReadmeMSDE2000A.htm downloaded from Microsoft SQL Server 2000 Desktop Engine (MSDE 2000) Release A

MSDE 2000 Release A: How to Use SAPWD switch to Suuply the SA pass

Is it legal to install Client Tools Only to manage MSDE?
I just called Microsoft and they said it was ok
source: MSDE and Client Tools from SQLServer Eval