Instant Messaging Client Between Linux-User And Win Xp-User Possible?

[gl556tr]

On my Win XP I have had Skype installed as the instant messaging client - no surprise there, as Skype is a MS product. I recently discovered that my HDD, on which Win XP is installed, will no longer start. As the display remains black and showing no hint of a problem, I feel that perhaps the MBR is no longer performing as expected. This was easy to alleviate with a diskette in the days of yore.
I have been able to start a web browser using a Linux on an USB memory stick; and then start the AnswerBank. But I do not know the Linux comparative SW to Win's Skype. a) Which Linux SW would perform this task?
b) Would I be able 'talk' to a colleague using Skype - and how can one achieve this?
c) Assuming there is a MBR problem on my HDD, how can one iron it out with a modern tool, presumably using a USB stick.
d) Could there be a starting problem other than MBR? Many thanks.

[Buenchico]

Skype runs under Linux:
http://www.skype.com/en/download-skype/skype-for-linux/