There are many restaurants within walking distance available for lunch

MLK library cafe/coffeeshop

San Jose Dining
San Jose Yahoo Dining Guide

Cafe Pomegranate (Persian/American), 221 E. San Fernando St (near 6th St)
White Lotus Vegan Restaurant, 80 North Market St (between Santa Clara and St John)
La Victoria Taqueria, 140 E San Carlos St AND 131 E Santa Clara (near 4th St)
Iguana's Taqueria (Mexican "burritos as big as your head"), 330 S. 3rd St
Mucho's Mexican, 72 East Santa Clara St (between 2nd and 3rd)
Inca Gardens (Peruvian), 87 East San Fernando Street (near 3rd St)
Togos Eatery (sandwiches), 125 Paseo de San Antonio (at 3rd Street)
Peanuts Deluxe Sandwich Shop, 275 E San Fernando St (between 6th and 7th)
Grande Pizzeria (also pasta), 150 E. San Carlos St (between 3rd and 4th)
Gordon Biersch Restaurant Brewery, 33 E. San Fernando St.
Mission Ale House, 97 E. Santa Clara St. (near 3rd St)
Melting Pot (French), 72 South First St (between San Fernando and Santa Clara)
Shalimar Indian Cuisine, 167 W. San Fernando St
House of Siam Thai Cuisine (very good), 151 S 2nd St (near San Fernando)
Hydration Co. (Japanese bento box lunches), 310 S. Third St (at San Carlos)
Dakao Restaurant good and cheap sandwiches and Vietnamese, 98 E. San Salvador St
Smile House (Korean), 86 S. First St (near San Fernando)
P.F. Changs China Bistro, 98 S. Second St (at San Fernando)

For those who can't live without the internet: San Jose Wireless Cafes

Google Map of the area