Note- Vista has ability to manage and shrink partitions->Start->right click 'Computer"->manage->Disk Management->click drive (C)->shrink volume
If you have XP or need to partition a space bigger than Vista will allow, follow this walkthrough with MEPIS:

Step One

download Simply MEPIS 3.3 here:
http://iso.linuxquestions.org/mepis/
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Step Two (requires DVD/CD burner -/+ R/RW)

Burn it to CD/DVD as an ISO image

Vista's Default burner does not include ISO imaging software, It can be downloaded here:
32-bit version
64-bit version

Step Three

Boot from the CD drive, put Linux CD in drive and boot. It will run Simply MEPIS from the CD, but it will not install

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Step Four

Sign in as: root, password: root

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Step Five

Click on "Run QTParted"- that will open a box showing your partitions. The main Windows partition is usually /dev/hda1

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Step Six

Right click on your Windows partition, and choose RESIZE

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Step Seven

In the box labeled FREE SIZE AFTER, type the size (in MB) that you want the new partition to be. That will create free space.

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Step Eight

Right click on the free space, click on create

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Step Nine

Select partition type (NTFS or FAT32), click OK

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Step Ten

Click on file(top left), then commit- changes will take effect

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Step Eleven

Click close, then click on the K in the lower left of screen and logout, restart computer

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Step Twelve

remove CD and it will boot to windows, check your partitions.

Insert Vista OS to install on new partition
OR
For XP installation on new Partition, see page 2@ http://www.syschat.com/dual-boot-vis...eady-1946.html)

The other tutorial link you posted at the bottom confuses me. It says to pick the drive with 100% on it, I have two for a start, and I dont have the option to shrink any of them. As for my main HD, when I do try and shrink it, it only lets me do it by 300mb and no more.

http://www.coflash.com/stuff/disk.jpg

I assume you already have vista, and are attempting to install xp as a dual boot-
You want approx a 40 GB partition for xp on your C drive (or just split it 50-50) then change that partition to D and your recovery to E. Install XP on D partition
use this walkthrough to partition your hard drive. When you have it partitioned and are ready to install xp on D partition click the bottom link for that walkthrough- but go to page 2, and start from there.

all i did was install vista on 1 hd and xp on the other.

poof dual boot. nothing more nothing less.

But it wont let me, it only lets me do 300mb, and there is no option to split it.

I installed xp first on hd1, then vista on hd2.

then i booted and Vista said :

what o/s do you want to boot?

earlier version of windows

microsoft windows vista

philljc-
your hard drive is already partitioned. your primary partition is c. partition and format it. the reason you cant under vista is because it allocated space for things like restore/recovery/page file. partition it with mepis, let vista adjust itself to its new partition size and then install xp on the newly created partition.

Oh I see. Sorry I am partially retarded.

Sorry to be a pain in the side, but what do I have to do to uninstall Vista and just have XP on here? Is it the same process for any computer, or do I have to worry about some dell stuff? Also, if I do a complete system recovery, will it install Vista again?

yes your recovery is vista.
put xp in, delete all partitions, format, reinstall