There have been issues surfacing lately when using 64 bit Server as either Web Front End (Web Application) Servers or Search Crawling servers. As we get more information, I will try to keep this post updated. But, I wanted to alert you as fast as possible, so this is a short post
1. Many 3rd party Web parts were written for 32 bit systems and may fail if you upgrade to 64 bit Web Front-ends. Please test all of your Web parts on 64bit WFE servers before changing hardware in production.
2. If you are using 64bit server to crawl content sources (remember, all WFE servers are doing your crawling by default), iFilters such as the Adobe PDF iFilter will not work. Once again, test all system components on a 64bit test server before upgrading/installing production hardware.
Ben Curry
Mindsharp