Windows XP support ends on April 8, 2014 – per the Citrix post. That right there is plenty reason to get your Windows 7 migrations planned, started, and completed in the next 2 years (at least). But, Penny Gralewski (old App-DNA buddy prior to the Citrix acquisition), has some extra reasons and also has posted up a very useful Windows 7 migration checklist.
Check it out!
The full post: Windows 7 Migration Checklist Accelerates Your Two Year Plan
The Checklist (PDF): Windows 7 Application Migration Checklist