I have a love-hate relationship with winamp... On one hand, I've been using it for a decade, it does what I need it to, and the media library is great. On the other hand it suffers the plaque of AOL -- dozens of thirdparty services, spying on music usage, and has become bloated to the point I wouldn't mind a replacement...
For movies/videos (of which I watch a lot), I prefer Media Player Classic, along with the Haali Splitter, Dscaler5 MPEG codec, AC3Filter, and FFDShow (all the codecs you'll ever need).
PS: OP -- Yes, the Zune is supported by Winamp (as are all PlayForSure devices, or any PMP that connects as a usb drive), though it's re-foldering/naming scheme it uses when syncing is ridiculous. MediaMonkey is great for syncing with PMP's -- custom folder/renaming settings, optional re-encoding (so you can turn your FLACs to MP3's when syncing) -- it's just a little buggy...