I installed Netbeans then I tried to checkout my projects inside Netbeans. During the process Netbeans informed me something about an old client version of subversion, and now I want to upgrade it. But I don't know where the client is, nor how to update it.
BTW I have TortoiseSVN on the same machine and it works fine with the same repository, and as I use svn+ssh protocol, I configured Netbeans to use TortoisePlink.exe.
If it's the Netbeans module you want to upgrade, just go to Tools | Plugins and it will tell you if there are any updates to be applied. Otherwise, if you keep your TortoiseSVN up to date, then you should have the latest client code. If, for any reason, you need a command-line subversion client, you can download the latest and greatest from here.
If it's something else, please post the specific message you get from Netbeans.
If you want to update your svn from netbeans you will need to go to Tools|Plugin and apply for updates, if you want to use some other SVN client you have installed in your machine you could tell netbeans to use it going to Tool | Options |Miscellaneous | Versioning then select SVN and indicate the folder that netbeans should use as SVN client.
Hope this helps