Oh my PowerPC Macs, Safari is far to unstable ( the latest release for PowerPCs anyway ). Its slow, and crash's constantly. So I use TenFourFox on my PPC Macs.
Safari on my new iMac is just, well. Not very good. I hate it. I'm sure some people like it, I hate it on Windows and I hate it on OSX 10.7. Its slow, cumbersome, and just poorly laid out. At least for me. Im sure some like it.
iTunes is something I tend not to use on Windows, I use the Zune Store/Software/Zune MP3 player. None of that music from the store will play on iTunes to start with. On my iMac I use iTunes most of the time.
For me, compared to the Zune software, iTunes is very slow, it feels very dated and sluggish, its not as refined, I just don't like it. Kinds reminds me of Vavles steam.
On my PPC Macs, Ten Four Fox and iTunes
Windows, Firefox and Zune.
Intel iMac, Firefox and iTunes.