Beijing Capital Airport (PEK) is NOT designed as a connection hub for transiting passengers. You will feel very inconvenient if your flights transit there. However, the new Terminal 3 (under construction) will have comfortable transit area and facilities. It will open in 2008 before the Olympics. Also, the existing Shanghai Pudong Airport (PVG) is a good choice for transitting people, and you won't need any transit visa there unless you're a citizen of the USA or UK.