NEW YORK/SAN FRANCISCO, Nov 11 (Reuters) - Hewlett-Packard Co struck a deal to buy network equipment maker 3Com Corp for $2.7 billion to step up competition against Cisco Systems Inc and expand into China. HP said it would pay $7.90 per share for 3Com, or a premium of 39 percent over its Wednesday closing price on Nasdaq. The move comes amid a flurry of acquisitions by Cisco and other technology ...