The familiarity of a card game such as Hearts, a word game similar to Scrabble (for example, check out Literati or WordRacer at YahooGames), or puzzle games like Bejeweled is comfortable for people of all ages and from all walks of life.
From bejeweled invitations to one-of-a-kind designs conceived by you and their design team to invitations that are delivered to your guests as beautifully-packaged scrolls, these party calling cards could never go unnoticed.
Big name games continue to appear on the system (like the incredibly well-received Gears of War) and the online service, Live Arcade, lets owners download casual games such as Bejeweled and play them in their living room.
This is assuming that we're not including things like Windows Mobile-powered Pocket PC devices, cell phones, and other portable electronics that are capable of playing basic titles like Bejeweled and Monopoly.
Popcap is actually the creator of both Bejeweled and Bookworm, but because of its partnerships - and of course, the popularity of its games - you'll find those games on Pogo, Shockwave, and Popcap's own site.