XP/Vista Dual boot

Ive done this before but reverted back to XP only after some computer problems I had but Im planning on doing a dual boot with XP Home and Vista Ultimate. Im using Partition Magic 8.0 to create my partitions and I cant remember if Im supposed to create a logical or primary partition for Vista (XP is preinstalled). And how large should the partition be for Vista Ultimate?

Last time I had 3 partitions (XP, Vista, and a third partition for shared documents between each OS). The 3rd partition had all of my documents located there. Is this the best option for keeping files synchronized for both operating systems? Thanks.

 

Someone I know is looking into the same thing so I was poking around. It seems that Vista boots differently then XP and having them on the same HD is NRP. Vista will clobber the XP. Two hard-drives are recommended and then it sounds tedious having to disable the one not in use. I suggest you do more research before continuing. Below is some info I found:
http://forums.cnet.com/5208-12546_102-0.html?forumID=133&threadID=312655&messageID=2884454&tag=forums06;posts#2884454
>>The way that allows you to use both OS's without either OS conflicting with the other is to use 2 separate drives. Put XP on one drive. Unplug that hard drive. Put Vista on the second drive. Plug in both drives. You now have 2 separate systems that do not cause incompatabilities. When you wish to change the disk that boots you can just do it in the BIOS or make the change when the computer boots up--if your BIOS allows you to.
Before using this method every time i did the 'standard' way to dual boot the System restore always was messed up<<
Wikipedia:
>>Booting sequence

The sequence of booting Windows Vista is slightly different from any previous version of Windows that uses the NT kernel. First, when the computer is switched on, either the BIOS or the EFI is loaded. In the case of a BIOS system, the MBR of the boot disk, which can be a hard drive or external media, is accessed, followed by the boot sector of the drive or of relevant hard disk partition. This boot sector then loads the rest of the boot blocks. For Windows Vista, the boot sector loads the Windows Boot Manager (Filename:Bootmgr.) which accesses the Boot Configuration Data store and uses the information to load the final stage, the Operating System.<<