Okay, I sort of misunderstood your problem with Outlook.  You're actually missing the "Send/Receive" button on the top toolbar.  You can right click anywhere on an empty space of the tool bar area and select Customize from the drop down list that pops up.  From there, you can add or remove any button you like from the toolbar.  I'm not really a big user of Outlook and so I had to set Outlook up on one of my computers here.  Hope that works for you.

In Eudora, would you by chance happen to have "Allow authentication" checked?  If you do, uncheck that option and try sending yourself a test email through Eudora.  These options are located in the Getting Started and Sending Mail sections.  Let me know if that doesn't work as well.

You said you were using a serial cable with your Epson printer?  Do you mean parallel cable?  Anyway, I did some poking around on Epson's support page and it wasn't too helpful (surprise, surprise).  If you right click on My Computer and select Properties and then the Device Manager tab, are there any devices that have an exclamation mark next to them?  Also, when you reinstall the drivers and software for the printer, does it say that it was successfully installed?  I believe that on some Epson printers you'll need to deactivate the Epson Status Monitor from the system (CTRL-ALT-DEL and then End Task it) before uninstalling the software.  If the drivers and software was installed correctly, try running a self print test and let me know if it passes that or not.