PST compression in OL 2002

I have posted this message on 1-10-05, but no one has responded - any help
here would be great guys!

I have a client who is running OL2002 and his file size was around 1.8Gb in
size. I archived the file by date and this produced a primairy PST file of
1.6Gb in size and an archived file that is approximately 1.8Gb in size. I
have tried to compress the archive file, but when I click the Compact button
(with the file selected) it says "compressing" for about 4 seconds and then
disappears.

1) I don't understand how I can archive a file of that size (choosing
archive dates of 6 months back to try and really get alot archived)and STILL
have a 1.6Gb file size.

2) Why can't I compress the files any further?

Thanks!

SRich