when i download the client do i just click the link to download it and let it go or will is there something i need to do since i got the most recent client?
You will want to install it to a new directory, so it won't conflict with your production installation. For example, production I think installs to %program files%\EA Games\Ultima Online or something. You can elect to install Renaissance in C:\Ultima Online\ (preferred).
It will make a new folder during the installation, if you tell it to. There is one step in the installation that shows the path and there's a button to change it and you can just type in C:\Ultima Online\
so if i do that it wont mess with my most recent patch and still be able to play on other servers that need the most recent patch?
'ey make sure you come by the shard's chat room and hang out. Modern day Brit bank. Although no one can see your pixels.