you'll love these pedals even more as you ride 'em... I ride zero's because I need no float to stay locked into a forward (straight) position...
BTW- pick up the May issue of bicycling magazine too... there is a decent article in there about adjustments to make in regards to different types of knee pain... if your knees are hurting you may need to make some adjustment to your fit... I had my seat moved up and forward and it's helped my knee problem a TON! Since doing that I have successfully ridden 3 centuries... one in feb, one in march, one in april... good luck and enjoy the speedplays!
There is a fine line between "hobby" and "mental illness".