UI and non-Betty HUD sounds from Mechwarrior/Mechcommander games; Mechcommander, Mechcommander 2 (both UI only), Mechwarrior2 (HUD sound only), Mechwarrior 3 and Mechwarrior 4 (UI & HUD sounds).
Huge thanks to Dak Darklighter from MWO forums for providing the raw sound files
Mwomercs.com
That face, every single time.
I2.kym-cdn.com