>Well, the application is a small ERP for PYMES (banking, accounting, crm, etc).

In this case, I will only choose EntLib if your team is quite proficient already in .NET and they have a good understanding of architectural patterns or you have a solid architect in the team. EntLib is really for Enterprise development. It can be daunting if you are not well prepared.

>It will be web based (asp.net 2.0) framework 2.0 , C# 2.0 in the server, I am the owner of the database...
>
>Thanks for your considerations. I will be testing some tools for a while... but not orcas yet.

If you will be doing web development, you could really take a look at VS 2008 (Orcas). From a deployment standpoint, it is just a small change over .NET 2.0, but the IDE and the language extensions are very good, and if you start now in .NET 2.0 you may find yourself tempted to do major changes later. Also, VS 2008 allows you to target .NET 2.0 projects, and it limits your developers to stick to the appropriate libraries, language features, etc.

For a web application you may even go live with betas or previews now. Do you plan to release something before year's end? Even so, I already have some web applications running on .NET 3.5 without major problems.

I think you should consider it.

Regards,