What's the extension of the first one? .rar? Winrar 3 is usually intelligent enough to put together various different numbering formats - r00, r01 etc. just happens to be the default it makes, although it can read others. Even if it's not rar, but a zip (which I think it might be), Winrar should be able to recognise them anyway if you open the first one in the lot (usualy the one without the weird numbers).