Replay Music is a very unique software. I haven't seen any alternatives for it. Other software require you to split songs manually. There is a free alternative for tagging songs, however it is much much worse than Replay Music.

Hopefully Replay Music for Windows Vista will be released very soon.

If I'm not mistaken a legal user of Windows Vista can legally install Win XP or 9x and use it for free. So you may install WinXP. You can make a separate installation or use it on a virtual machine like VMWare.

p.s.
Of course there are audio stream rippers that can rip MP3 from shoutcast/icecast radio stations. Many of them can split and tag songs automatically. While ReplayMusic can record music from any web radio station, shoutcast rippers support shoutcast compatible radio stations only. But unlike ReplayMusic that records sound from your sound card, shoutcast rippers download (rip) music files from web radio stations.

iRadio is another radio ripper. It supports not only ShoutCast, but also Windows Media, Winamp Live 365 and QuickTime Darvin audio streams. It can save audio tracks to separate files with corresponding file names.