[R] make a right subset!

[chalabi.elahe at yahoo.de]

Hi all,
I have 2 data frames like the following:
the first one df1:

    'data.frame':  141obs. of 1 variable:
    $SerialNum: int 41006 41013 41044 41046 41067 41166 41202 41262 41274 41290
and the second one df2:

    'data.frame':  194 obs. of 2 variables:
    $Serial: int   41006 41013 41018 41044 41046 41067 41111 41200 41262 41331 
    $Count : int   1 10 103 11 12 13 138 14 15 16 169 18 182 2 20 21  224 226
then I find the intersect of two data frames in serials which is:

    Matched=intersect(df1$SerialNum,df2$Serial)
which gives me matched serials in both data frames. Next I want to get Count of these matched serials from df2 but I don't know how to make the right subset for this! Does anyone know how should I do that?
Thanks for any help,
Elahe