There is no real machine you can switch to, but you may install virtual machine like QEMU to install XP (be warned, extraordinarily slow) and emulator like DOSEMU or DOSBOX to run DOS.
thank you ,i know ,but how can i boot my os, grub?and i donit know how to use grub for boot ing dos,and the dosemu that you recommended is the same as virtual floppy,so it can't work! so?
grub可以启动软盘镜像,比如启动windows3.11,当然dos也可以:
title Win311 from Dos from Floppy image 1.44Mb, just for fun...
kernel (hd0,0)/boot/memdisk
initrd (hd0,0)/boot/win311.img
boot
这些镜像文件网上很多。