Paint.NET v3.5 has added support for DirectWrite, a new component in Windows 7. It improves performance, text rendering quality, and reliability when compared to GDI+ or GDI.
DirectWrite is also coming for Windows Vista. Microsoft just released a beta version of the “Platform Update for Windows Vista”, which includes Direct3D 11, Direct2D, and DirectWrite. Check it out here: http://blogs.msdn.com/DirectX/
Paint.NET will automatically use DirectWrite if it is installed on a Windows Vista system. The code for enabling DirectWrite does not limit itself to Windows 7. You don’t even have to wait for the next update, you can do this now! This is all pre-release beta stuff though, so the usual warnings apply. The next update after Paint.NET v3.5 (let’s call it v3.5.1) should automatically install this for you, so that’ll be one less thing to have to remember (computers are good at automating and remembering things, right?).