Extraction command and fink conflict

[Sbranzo]

I used to have fink installed, because I needed a working postfix. Now
postfix is ok under macports so I want to remove fink.
If I move /sw to /sw-old, for example, here's what I have If I try to
install some new program in macports:

sudo port -vc install unix2dos
[...]
--->  Extracting unix2dos-2.2.src.tar.gz
sh: line 1: /sw/bin/gtar: No such file or directory
gzip: stdout: Broken pipe
Error: Target com.apple.extract returned: shell command "cd "/opt/local/var/db/dports/build/_opt_local_var_db_dports_sources_rsync.rsync.darwinports.org_dpupdate_dports_textproc_unix2dos/work" && gzip -dc /opt/local/var/db/dports/distfiles/unix2dos/unix2dos-2.2.src.tar.gz | /sw/bin/gtar --no-same-owner -xf -" returned error 127
Command output: sh: line 1: /sw/bin/gtar: No such file or directory

So I tought installing gnutar under macports could be of any help, and
mv'ed back /sw/ from /sw-old. Installation was smooth, because port used
/sw/bin/gtar to unpack tarballs.

Then I moved /sw to /sw-old, expecting macports will use the new
gnutar, but the problem is similar:

sudo port -vc install unix2dos
[...]
--->  Extracting unix2dos-2.2.src.tar.gz
sh: line 1: /sw/bin/gnutar: No such file or directory

gzip: stdout: Broken pipe
Error: Target com.apple.extract returned: shell command "cd "/opt/local/var/db/dports/build/_opt_local_var_db_dports_sources_rsync.rsync.darwinports.org_dpupdate_dports_textproc_unix2dos/work" && gzip -dc /opt/local/var/db/dports/distfiles/unix2dos/unix2dos-2.2.src.tar.gz | /sw/bin/gnutar --no-same-owner -xf -" returned error 127
Command output: sh: line 1: /sw/bin/gnutar: No such file or directory


Now it looks for /sw/bin/gnutar, the name has changed (it was gtar before).

Why does port look for commands in /sw/bin? I used to have
/sw/{bin,sbin} in my path (and in root's path too), but now I removed
all the references.

Thanks in advance,
Gufo