Tapsnake virus detected on my MAC...recommened to download Mackeeper to remove virus..is this software legit?

No, it is a scare tactic to get you to buy a subscription to MacKeeper.

In addition to all of the other bad things about MacKeeper, it has recently been discovered that it has a security hole in it which will allow other access to your Mac. MacKeeper is to be avoid.

Do not install MacKeeper (and how to uninstall it if you have):

https://discussions.apple.com/docs/DOC-6221

It contains a major security flaw, recently noted:

http://www.macnn.com/articles/15/05/08/contentious.utility.ignored.apple.guideli nes.created.zero.day.exploit.128538/

There is currently a class-action against MacKeeper:

http://www.macworld.com/article/2927032/ads-for-mackeeper-refunds-will-run-on-fa cebook.html#tk.nl_mwbest