R help - Aug 2004 - Adjusting two continuous variables by one continuous variable

Hi,

I want to look at the relationship between 2 continuous/quantitative variables
while adjusting for a third continuous variable. For example: relationship
between height and weight adjusted for age.
As I understand it using a glm would work if I had a categorical variable (I
could make age into a categories) but I am interested to know if anyone knows
how I can do this analysis with out making age into categories.

Any help would be appreciated.
Cheers
Peter