Amid all the speculation of the "imminent" release of a new MacBook, I'm wondering about the practical usable life of the current MBs. May give up the wait game soon and get a replacement for my trusty 12" PB, which is starting to really wheeze in Leopard and even MS Office '08. But I wonder, given advances in apps and tech, whether a couple years or even less down the road I'll be muttering "gotta get a faster machine!" My uses are modest--Office, Dreamweaver, light work in graphics/video/music. Since I'll be getting a US keyboard but using in Japan, reselling ain't so convenient. Any input appreciated.