Hi all .. am using Ubuntu 8.10 32-bit & I want to upgrade it to 64-bit .. is their a way to upgrade it without uninstalling the software & is the 64-bit version working good & applications works normally with it, Thanks.

I highly doubt it, at least not without a lot of effort. Both the kernel and the applications it runs must be compiled for 64-bits to have a true 64-bit distro. While it's possible to also run 32-bit binaries under a 64-bit kernel (on x86_64 chips at least), they require the presence of a separate 32-bit support layer and libraries and such. This is useful for running the occasional program that doesn't have a 64-bit version, but it's no way to run an entire OS. You're much better off simply reinstalling the whole thing from scratch.

Well upgrading hmmm...

You can simple install the 64 over the partition of 32bit, so u won't lose /home data
If you don't format you're partition heheh XD

But Programs are needed to be reinstall i guess