Can I backup my W2K3 32 bit single server environment (AD, DNS, IIS etc) and restore it to the same box with a W2K3 64 bit installation?

I'm 99.999% sure the answer is no. Content such as your actual AD database, your web content, DNS db, etc. should be fine. It's the metadata, server config files, etc. that are gonna be the problem. "Enough, enough bowing down to disillusion! Hats off & applause to rogues & evolution! The ripple effect is too good not to mention. If you’re not affected, you’re not paying attention!"

but if it was just the AD, DNS and IIS, do you think it would work, can't find much info on such a scenario on the net. thanks for your reply by the way.

What you're asking really doesn't make sense. If you're planning on upgrading to a 64 bit OS then by all means, do a backup with the 32 bit in case of problems and you have to roll it back to the 32 bit OS. If the upgrade/clean install goes well, perform a backup within the 64 bit OS immediately.

sorry, maybe I'm not being too clear. I currently have a W2K3 32 bit setup, single server environment running E2K3, it's been running for a couple of years and is stable. To install E2K7 I need to have a 64 bit platform for it so sit on, so want to upgrade to W2K3 64 bit. Since there's no upgrade path, I'd like to backup my AD, DNS, IIS, then wipe the box for a 64 bit installation, then restore the AD, DNS IIS from my 32 bit server. Do you think that's feasable? Have you come across any documentation on such a scenario? Thanks for your help and advice.

#1. Most migration paths for Exchange 2007 involve moving the mailboxes to a new server. #2. You shouldn't be running Exchange 2007 on a DC. (AND YOU'RE ABOUT TO FIND OUT WHY!) #3. You're actually kinda screwed anyway since your current server is a DC. You need to rehome your public folders and uninstall Exchange 2003 before you can DCPromo down your DC, and you can't do that without collapsing your domain since it's the same physical machine you want to be your new DC/Exchange server. I see a future wrought with pain and suffering. I would suggest setting up a temporary DC/Exchange 2003 server, make it a GC/DNS server, allow replication to happen, move your mailboxes to it, rehome your public folders, transfer FMSO roles, uninstall E2K3 from server, dcpromo it down, disjoin from the domain, reinstall Windows, promote it to DC/GC, setup DNS on it, allow replication to occur... *deep breath* ...Install Exchange 2007 to absolutely ensure you have to go through this mess again in the future (why not learn from your mistake now, and have Exchange on a member server), move mailboxes and rehome public folders to it, uninstall E2K3 from temp server, transfer the FSMO roles back to the 64-bit server, and finally DCPromo the temp server down. WHEW! I'm out of breath. P.S. I highly recommend rethinking this whole running Exchange on a DC thing you got going on. It has performance, security, and tons of migration issues and pains down the road. "Enough, enough bowing down to disillusion! Hats off & applause to rogues & evolution! The ripple effect is too good not to mention. If you’re not affected, you’re not paying attention!"

ha ha, fantastic, thanks for the info, fortunately i have another server i can shift over to help with the migration