You may want to try Skype in Safe Mode with networking to see if the same numbers are produced. In case there is some odd issue with your profile, you can browse to the (windows key +r) %appdata% folder and rename Skype to Skype1 (when Skype is not running) to reset your profiles. Important data like your chat logs (main.db) will be located in your %apdataa%Skypeyourskypeid folder. You may have to transplant that at a later time to recover your older history. Memory usage for the Skype clients I run are typically below 100 up to 150+ or so. So I wouldn't be alarmed if it's using that much.