One of the customizations I did when I switched back to Windows was to find the best way to access my ext3 partitions. I already knew about explore2fs, a nice explorer-like ext2/ext3 browser, which lets you copy files from your Linux to your Windows partitions.
What I was looking for was a way to natively access my files (I have most of my reggae cds ripped as mp3 on my Linux partitions at home and at work), so I tried a few drivers and finally settled for ext2fsd as it's the only one that worked on my system. I've been using it for the past week and it works very very well.
To set it up, download the latest ext2fsd release (0.10), extract it somewhere, enter the Ext2FsdSetup folder, run setup and install the .inf file. To mount your partitions, use mount.exe in Ext2FsdMount.
I copied mount.exe in %SYSTEMROOT%windows32 (usually c:windowssystem32), and linked to my Start Menu Startup folder a .cmd file containing these two lines:
net start ext2fsd mount 0 2 h:
where 0 is the first ide disk and 2 is its second partition. Easy.