So, at my current job we're usually 1-3 developers, 1-2 art directors and 1 project manager on each project, with the smallest ones just being one of each and the larger ones being three developers and two art directors.
I'm looking for a software, combination of softwares or some type of service that will allow us to manage our projects individually, it's important that we're able to manage several projects at once within one system/piece of software (without going through a too complicated setup process for each project) since we usually have 2-3 ongoing projects in parallel.
We need to be able to integrate with SVN, Track bugs/features/request, Put up milestones and some type of agile management a´la SCRUM would be nice.
Preferably it should be able to run on Windows (without to much hassle, ever tried to put up Apache+Python+Svn+Trac on the same Windows 2003 server and get them all to run together? not fun.) since we mostly do .NET development and most of our servers run Windows 2003.
Since you seem to have a maximum of six people working in a single room - I'd give serious consideration to not using software at all.
A whiteboard & cork board for each project, plus a whole lot of index cards / stickies can go a long, long way towards meeting the project management needs of one or two small projects.
(Failing that - I've found basecamp a fairly lightweight tool for small projects - although it doesn't do any sort of source control integration. I've also heard good things about the latest FogBugz - but I've had such bad personal experiences of earlier versions I've not tried it yet myself)