You should read the Microsoft documents regarding the upgrade.
I also recommend searching the web and newsgroups for upgrade issues. Most of the articles I've found have been very positive about the upgrade. Most problems are minor though there have been some major problems experienced.
Some of our upgrades went smoothly. However, none of four-processor servers would complete the upgrade process and we had to uninstall SQL Server, install SQL 2000 clean and then attach user databases. To do this we had to script logins, jobs, DTS packages, etc. In Newsgroups, others have noted the same upgrade failure but no one has been able to determine the cause.
Here are some other minor glitches that we hadn't read about.
1) SQL 2000 send Mail attachmments as Unicode files where SQL 7 sent ANSI files. This caused problems for PCs running Win 95. A new registry option was provided in SP1 but this must be manually added. There is a knowledgebase article about this - Q280720.
2) xp_sendmail in SQL 2000 no longer copies sent mail to the Sent Items folder whereas SQL 7 does. Apparently this is by design and Microsoft has not indicated that an option will be added.
3) Some connections from EM, QA, Access, VB, etc. that worked in SQL 7 failed after the upgrade. We were able to fix the problem by adding an alias with the Client Network Utility.
Despite these problems, I like the enhancements in SQL 2000 and feel that the upgrade is worth the trouble. Hopefully, you won't encounter any trouble. Terry L. Broadbent - Salt Lake City, UT
Home of the 2002 Winter Olympics (Feb 8-24)