Yes, both Plaxo and AIM services are compatible with Outlook Express. Plaxo is an address book manager that can run with Microsoft Outlook 2000, 2002, 2003, 2007 and Outlook Express 6.0. All you need to do is to download and install Plaxo Toolbar for Outlook Express.
In order to configure AIM to work with Outlook Express, launch the Microsoft product and from the Tools menu select Accounts. Press the Add option, click Mail, type your name, click Next, enter your AIM email address, click again Next and select IMAP as incoming mail server. Type imap.aim.com in the Incoming mail (POP3 or IMAP) server field and smtp.aim.com in the Outgoing mail (SMTP) server one. After that, click Next, type your AIM user name under Account name, enter your account password in the Password field, press Next and then Finish. Also, select imap.aim.com from the Internet Accounts window, click Properties and open the Servers tab. Check the My server requires authentication box, open the IMAP tab, un-check the Store special folders on IMAP server option and press OK.