help needed

[naani]

respected sir/madam,

recently i have downloaded enigmail for thunderbird 1.5.0.7.
i am clueless regarding version to be downloaded.
i have come to know that version has to be downloaded according to the
operating system.
my system configuration is
windows xp  professional version 5.1.2600
system type : x86-based pc.

please help me to decide about the file to be downloaded.
please specify the name precisely and any other files to be downloaded.

i am awaiting for your reply.

vishnuvardhan.