Get the chip in first, change hdd, use SlaYers install disc as it is really good and will do all the formatting and installing for you. Sure you can do it all by yourself but I prefer using SlaYers as I like it and it is real simple.
Without the chip you will not be able to switch hdd or use SlaYers disc. The disc also has an option for formatting drives larger than the original one.
A little note, if you do choose the X3 use any good X3 bios from teamxecuter. Otherwise if you go for any cheapmod chip (such as aladdin or DuoX2) use EvoX M8+ if you have an 1.6 xbox and the X2 4983 if you have any earlier version.
Good luck and happy modding.
