C.,
Whether you serve lunch is up to you. If you do, sandwiches or hot dogs or pizza usually go well with fresh fruits and veggies and maybe some chips. You could have the kids help make lunch - put toppings on homemade pizza (or make mini pizzas with english muffins as crust.) Kids could also help make pigs in a blanket (roll hot dog in crescent dough triangle from a can.) I have also done spaghetti and meatballs with garlic bread. That went well.
At 5 year old birthday parties, they are just getting old enough to handle games without tears. I stick with the classics - hot potato, who's got the button, musical chairs, (if your birthday party has a movie theme like Star Wars, you can get the music soundtrack from your local library.) These games are free to prepare and kids love them. If you have the room, you can play duck, duck goose and change the names to fit your party theme. (Example: Mater, Mater, Lighting McQueen!")
Pinatas also go well at this age. I saw a mom prepackage treat bags with name labels and put them in the pinata. When it broke everyone had been instructed to get the bag with their name on it and help their friends find theirs; then they aren't killing each other to get the last Tootsie Roll.
One of my kids' favorite games is "Don't Eat Pete." You create a gameboard (piece of cardstock) with 9 or 16 squares and put a picture in each one. (Can go with your birthday theme.) Put a small treat (marshmallow, jelly bean, M&M) on each square. One child walks out of the room for a second and you point to one square so the rest of the kids can see. When child comes back, he takes the treats one by one until he picks the treat on the picture you pointed to..everyone yells "Don't Eat Pete!" and he has to stop taking treats. The last child who was "it" can be the one to pick the new "Pete" square. My kids LOVE this game. I did it at a Valentine's party for Kindergarten and second grade and it was a big hit there, too.
I have also read them stories at the end of a birthday party to get them settled down before their parents picked them up. Again, you can find books that go with your theme or just some birthday books from the local library.
Good luck,
S.