You need to provide a lot more details than the above to get a reasonably accurate answer. For example, what is the intended use for the server, what kind of OS and software will you run?
Since you are asking in the TortoiseSVN forum, I'm assuming you are looking for a server providing some sort of virtual desktops. TortoiseSVN will not require much in resources in excess of what you need for your other use cases. If you scale your server for your main use case it will cope easily with TortoiseSVN.
If you are thinking about building an SVN server (ie, hosting repositories) you can probably get better answers on us...@subversion.apache.org
or by asking the vendor providing your Subversion server (if you run one of the commercial distributions). The answer will depend a lot on the amount of data you plan to store and how you plan to use SVN, however my gut feeling is that for 50 developers committing normal source code, almost any server produced within the last 10 years should cope easily.