I would say it's fine for WoW.
Based on the specs for GW2, the minimum recommend integrated graphic core is the Intel HD 3000. That is more or less equivalent to a desktop Radeon HD 5450. The Radeon 7640G graphic core in the A8-4500m is between as powerful as a desktop Radeon HD 5550 and HD 5570; closer to the HD 5570. Therefore, it should be fine with low graphic settings on a 1366x768 resolution screen.
http://www.guildwars2.com/en/the-game/game-faq/
It should be noted that since the game has not been released yet, the system requirements may change.