Here is the list of the oldies that I just found:
AOL Instant Messenger 4.7 (build 2480, released on July 20, 2001)
MSN Messenger 5.0 (build 0537, released on October 24, 2002)
Yahoo! Messenger 5.5.0 (build 1214, released on August 1, 2002)
Skype 0.90.0.5 (released on August 29, 2003)
ICQ 2000b (4.70 build 3286, released on October 15, 2001)
ICQ 2001b (5.15 build 3633, released on October 30, 2001)
Avast! 4.0 Home (build 143, released on December 18, 2002)
Avast! 4.0 Professional (build 143, released on December 18, 2002)
Instant messengers:
AOL Instant Messenger 4.7.2480.rar (2.0 MB)
MSN Messenger 5.0.0537.rar (1.3 MB)
Yahoo! Messenger 5.5.0.1214.rar (2.2 MB)
Skype 0.90.0.5.rar (2.1 MB)
ICQ 2000b (4.70.3286).rar (5.2 MB)
ICQ 2001b (5.15.3633).rar (8.3 MB)
Installers:
aim95.rar (2.5 MB)
MsnMsgs.rar (2.2 MB)
ICQ 2001b Beta 5.15 Build #3633 Setup.rar (3.6 MB)
skype090.rar (2.5 MB)
ymsgr_beta.rar (2.6 MB)
ICQ 2000b Beta 4.70 Build #3286 Setup.rar (5.1 MB)
setupengpro.rar (6.1 MB)
setupeng.rar (5.9 MB)