没玩过两个扩展分区，多个主分区没问题。

你干嘛一定要在Primary 1上装Linux？弄得支离破碎的。搞个大分区不好吗？现在Linux已经可以装到40G以后的分区里，随你怎么装啦。

我的建议：
分三个Primary就够了。
Primary 1 for Windows 40G is enought for your daily system and app.

Primary 2 for your Linux. The size depends on your stuff.

Primary 3 as NTFS for your data exchange. Since NTFS write is still trail in Linux, better not write to system partition directly. But XP is sucks not reading anything other than NTFS/FAT/32.