the number one reason is email.
i've been using fetchmail/emacs/gnus for work email, but it does not work well enough for me "out of the box" to convert entirely for home use. the main issues are emacs/gnus handling of HTML and attachments.
TODO: try evolution. and/or mozilla.
TODO: try getmail (python fetchmail replacement).
TODO: try CRM114, SpamBayes, ...
2004-02-28: the problem is not really that i'm using Outlook to read my mail, the problem is that i'm using Outlook to store my mail. i'm now thinking that i should install an IMAP server at home for mail storage and access. then i can use whatever mail client i want. that's The Right Thing. the main contenders appear to be Cyrus and Courier.
2004-07-05: Today I tried Gnus 5.10.6 (as opposed to 5.9.0 which is still the default even on Fedora Core 2), and it works perfectly out of the box with respect to rendering hideous HTML messages as text. Nice! Maybe I should skip the IMAP server and switch to gnus at home too.
2005-06-18: Just installed Fedora Core 4 and it is still shipping with Gnus 5.9.0. WTF?