I use multiple tools. The criteria I look at is ease of use, support (this include free or almost free tutorials on using the tools), color highlighting syntax help, integrated debugging, the number of languages supported, cost, and how well can I integrate different parts. Here are the ones I find the most useful. Visual Studio, I like this because it works well with both web and desktop applications. You can get the express edition for free. Microsoft is the first IDE I saw with intellisense syntax help. Microsoft also offers a lot of free tutorials at asp.net and MSDN. Visual Studio supports C++, C, Visual Basic, XSLT, Java-Script, J#(Microsoft java) and you can get plug-ins for many other languages(Python, PHP, COBOL and many more).
I also like Komodo from Active State. This is really good for open source development it supports PERL, PHP, TCL, Python, Ruby, Java-Script and many more. It is not free but the Student license is only $49.00.
Eclipse has already been mentioned but what they didn't tell you was that it can be adapted to any language you chose. This is an advanced feature but many have already developed different languages and you can download and plug them in for free.
Finally I suggest a visit to www.thefreecountry.com you will find free compilers and IDE's for almost any language you have ever head of and some you haven't.