Hey guys, we are trying to evaluate linux in our enterprise, wondering, what parts within the enterprise, is Linux ideally suited for. Do you think, since Linux is a good replacement for Solaris or Windows. Which server do you think does the best job supporting Linux

This is an impressively vague question, which you can't answer in a forum. Parts? I don't understand how it could ever be said to be a good replacement for anything as a blanket statement. It's a pretty bad replacement for windows if you need to run software which only runs on Windows for example...

Why are you looking at Linux in the first place? The question seems so open ended that it's as if your heads of IT and Finance got together and thought "This Linux stuff is apparently free! Let's use it, whatever it is!" You need to have a proper reason to want to look towards it in the first place, or it's just pointless even thinking about it. Do you have a real scenario to give this some context?

As @acid_kewpie stated, you need to put to the paper what exactly you have now, and what you need it for.

In General, Enterprise Linux distributions are very stable, and scalable. The thing that brought me to Linux was that you can turn any generic PC into RAID based file server. Windows needs you to have $300 RAID controller to be able to create safe and scalable RAID solution, even if you only want to have 2 HDD's to mirror data. Fake RAID controllers in today's motherboards are hardware dependent and they need support from OS to work properly.

In a year's time, Samba File and Domain server for Linux is supposed to release stable version that will be able to replace entire Windows Active Directory server and you do not need CAL's neither to access server or to access A.D.

Furthermore, Linux is practically virus free environment, and in my opinion security is much better, or shell we say much easier to control and maintain, without expensive third party security software. One of the best examples of Linux in enterprise is Google, running from 10.000 to 100.000 (I do not know of any exact data) Linux-es all interconnected in clusters.

But Linux is not a golden bullet, you need to model your software to suit your needs, not vice versa.