Can I do an inplace upgrade from SLES 11 to SLES 11 x64?

[ttoepp]

I wasn't thinking clearly when I first installed SLES 11 to run as a XEN Server and after running I see that it is only recognizing 16GB of RAM. So when I look at the specs for SLES 11 is says that it will only recognize 16GB of RAM. But if I go to SLES11 x64 I will recognize more memory. Can I just boot from the SLES11 x64 DVD and install it over and will it keep all my current XEN Hosts? All the Server is for is XEN, so that is really all I'm concerned about keeping...

Thanks in advance for the help