I think those are Real Media files, made for Real player (heard the player sucks big time so I make sure it doesn't come anywhere near my Mac).
I tried looking in Google but there doesn't seem to be a converter (I didn't look thoroughly enough though)

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iMac G4 OSX 10.3.9
RAM 256MB
LW 4.10.5 Basic
ADSL anything from 3 to 8Mbps/around 1024kbps

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