Upgrade from ESXi 5.0 to 5.1 U1

Hello,

I usually do clean install when upgrading ESXi. This time I want to do with Update Manager. I imported "VMware-ESXi-5.1.0-Update1-1065491-HP-5.50.26.iso" custom HP iso to update manager. And scan the host, it founds the upgrade iso .My question is I would like to keep my standart switch config. And second concern, driver upgrades should be done.That's why I downloaded HP custom iso. Doing with update manager, this way will it keep the standart switch config or I have to do it the config again after upgrade ? If I am not sure, I will do it with CD installaation selecting upgrade option with preserving VMFS datastore.

Thanks,