M.C.
A., before you decide to follow the CIO advice from others, please read this article:
http://www.mothering.com/articles/new_baby/bonding/connec...
Ultimately, you have to follow your own instincts and heart and do what is best for your family. We cosleep, and even though I am a light sleeper, I find it easy to nurse my DD back to sleep, even though she wakes every 1 to 3 hours at 14 months of age. As long as I go to bed early (9 am) I feel rested for the day (I am a SAHM though). Some nights are tough (when teething, etc.) but I keep in mind that this too shall pass and soon she won't want anything to do with me and I'll treasure these moments when she was a baby.
Babies should not want to be alone; otherwise how would we have survived as a species? But it can be hard on the mother in this modern age. I find cosleeping and attachment parenting gives me the tools to gently respond to my DD's needs.
However, cosleeping does not work for everyone. Jamie V gave you good websites about attachment parenting and sleep. I espy like Kathy Dettwyler's explanation of infant sleep. You can also read Pantley's "The No-Cry Sleep Solution"...others have found her gentle, responsive methods helpful.
I firmly believe that a baby should never be forced to cry alone (unless the caregiver needs to step out of the room for a quick sanity break).
HTH, M.