SQL Server 2005 32 bit and 64 bit are almost identical so this shouldn't have any effect. The difference is that the 64 bit version can handle larger amounts of memory better above 2Gig, so your host is able to cram more databases onto the server.
If you are still looking for hosting then the
Web Wiz Host hosting with SQL Server is very fast, just look at
www.speakerplans.com/forum it has over 60 active users most of the time and it flies along. We have also just put another server online, to keep the severs as sparsely populated as possible, so if you sign up today you would be on a new Quad-Core server, with just 2 others sites on it!!
We have also just put on a new Corporate Hardware Firewall with improved throughput to speed things up some more and keep everything safe from malicious attack as well as upgrading our network to 1Gbps and providing two 1Gbps network connections from each server.
Moving your site shouldn't be to much of an issue we can setup the forum for you and help move the database, you would just need to upload your websites files.