With the release of labview 7.1 you have a new structure in LV called timed loop which will let you sychronize up to 128 loops precisely in one application. On windows platform you can get rates up to 1kHz. If you need more precise measurements like 1MHz then you need to move your application to LV RT
http://sine.ni.com/apps/we/nievn.ni?action=display_offerings_by_event&site=NIC&node=64000&event_id=14215&event_subtype=GENERAL
