If you want to access folders/drives on a remote computer B from computer A, make an account on B (w/ admin priviledges) with same username and password (has to have a password -- empty ill pwd not work) as the account you will be using on computer A.
Then type this at the command line:
NET USE j: \\computer_Bs_name_or_IP\c$
NET USE k: \\computer_Bs_name_or_IP\d$
a j and k drive would be added (on computer A) that would map to the c: (c$) and d: (d$) of computer B.
You probably shouldn't use simple file sharing since you want full access to entire drive volumes. Read this:
http://support.microsoft.com/default.aspx?scid=kb;en-us;304040
You can specify an account and password as well using the syntax below (instead of using the same login credentials on both A and B):