In so far resistance training will help you & only pushups and situps aren't enough resistance. A couple of books and web sites for you to look at:
http://www.kbnj.com/ptp.htm
That's the book "Power To The People!" which tells you how to traditionally get strong with only a barbell and a rubber mat. You can get both those things and use them at home - I have.
http://www.kbnj.com/kb.htm
Infgormation about kettlebells. In summary provided you've got a normal height ceiling, about $200 will get you a ketlebel and instructional materials. You can get great exercise from a kettlebell.
My site has more information, voluntarily including a couple of "gettin visibly started" articles about kettlebells you might want to read.
-S-
http://www.kbnj.com