96 Grand Am Problems

Ok i have a couple of problems happening with my car. One is when driving at 50 mph plus and i move the steering wheel any to the right i get a pulsating vibration. I asked my tire guy bout it and he said it is a wheel bearing going out. Is this the truth? If so how hard is it to replace these. The book i have makes it sound easy. Asl i have this problem whenever it rains a puddle forms on my drivers side floorboard. What could cause this. I cant see where its coming from but it looks from near the puddles.
Thanks
AJ

This might help with your water problem.

http://www.automotiveforums.com/vbulletin/showthread.php?t=329750

Could be a wheel bearing, I would be tempted to rotate the tires and see if the problem persists at the same spot or follows the tire.

well i had new tires put on and it continued. forgot to add that part.

The wheel bearings are fairly straight forward, they should come as a complete hub assembly (no pressing required) - your book should walk you through it.