请教一个问题，普通的硬盘可以允许几个主分区,拓展分区。。

我的电脑只有一块硬盘，没法再加了。 装了双系统后 winxp, linux，发现用继续分割硬盘(partition magic)有困难。 现在考虑重装一次，不过需要先计划好如何分区：
my current partition table looks like this:
windowsXP: 2 primary partitions.
linux : 1 primary(/boot), 1 extended partition.

since I need to have 3 partitions for windows, the current scheme is no good. i was wondering if it is possible to create 2 primary partitions and 2 extended partitions on my hard disk, like this:
winXp: 1 primary,
1 extended:
-logical partition, for backup
-logical partition,for filesharing with Linux

linux: 1 primary(/boot), 1 extended partition(/root, /home).

Any help? Thanks very much..