[gpvos]

There may also be links to your home directory as "Desktop", "My Documents", etc. See winecfg for these. And note that your registry files may refer to Z: (mostly for fonts, it seems), or even directly to files outside your Wine directory.

[CyberShadow]

If the software is Wine-aware, it doesn't matter. The \\unix\ filesystem namespace allows programs running under Wine to access the host filesystem whether it's mapped as a drive or not. And, of course, since Wine Is Not an Emulator, it could also use POSIX APIs or Linux kernel syscalls directly if it wanted to.

[gpvos]

Have there been reports of Wine-aware malware already? (If not, the next generation probably will, though.)