There are now fully downloadable, offline versions of the Angry Birds games and do not require a browser to play. Both games run in windowed or full-screen modes.
If you download the demo and like it, you can upgrade it via Paypal or credit card. Rovio will then email you a serial number to unlock the full game. Angry Birds has been available on the Intel AppUp store previously but is now available directly from Rovio.
Download Angry Birds for PC’s at the Angry Birds PC Shop! There you can download a free demo of Angry Birds, Angry Birds Rio and Angry Birds Seasons for your PC. To unlock the full versions, you can purchase an activation key for each game. Have fun playing Angry Birds! Squawk!