Greetings Morten,
First lets take a moment to review what class413 posted. "1. I don't know if w!nxp would be happy to not be The First of all.." I agree wholeheartedly. I suggest strongly that you place WXP first, as it not only will have its own slice but will put a est 8mb MBR slice in front of it. I am pretty sure that Grub is booting the WXP MBR, which in turn boots Windows. If you delete or take away that 8mb or less slice, Windows may not boot properly.
Determine how much space you want WXP to have, ideally leave 25% empty space on the Windows slice so it can defragment, and whatever. My experience has shown that the traditional 10% is barely enough. We don't want to have to mess around with Windows, so give it 25% and call it done.
Secondly, class413 states this: "2. You can't have that partition scheme in a x-86 computer. Hard disks in those systems can contain- up to 4 principal partitions, " then you are informed how to add more slices if you want. The 4 slice standard is best for now. When you start extending slices and so on, you will run into a ton of issues you may not be prepared for. So for now, consider just 4 slices. (Grub doesn't see the 8mb MBR as a slice, as it uses it for booting Windows).
So you have some pretty good advice from class413, now lets look at your proposed hdd layout. My, you are quite adventurous to consider those particular OS's, but take note; some of them are pretty much duplicate. If you are trying to learn Linux & Unix; and are regulated to 4 slices...there is a better layout.
You have Solaris 10, which incidentally is one of my favorite operating systems, simply the best. lol But take note, it is a basic corporate variation. I strongly suggest you step up to OpenSolaris Developers Edition. It is free, includes everything Solaris 10 has, and more. And it comes with tons of support and forums and such. I adore it.
Next you have Fedora, I don't know much about Fedora...some say it is like BeleniX (which is built on the solaris kernel). But I do know about Red Hat, it is certainly a decent OS, if you are determined to use Linux.
Now the FreeBSD. Take note: ALL of the BSD commands work in OpenSolaris, that is more of the beauty of this spectacular OS. It uses both V and BSD commands. Solaris 10, doesn't take BSD commands and BSD doesn't take Solaris 10 commands (V). But OpenSolaris takes both, so drop FreeBSD. (Better yet, buy yourself one of those cute little Apple boxes and run BSD on that.)
Next, Debian 64 bit & Debian 32 bit. I have used Debian a bit and consider it the "Crown Jewel" of Linux. Take note. the creator of Debian, is now working for Sun on the OpenSolaris project. I am assuming you know that Debian and Fedora use different commands. (How different I do not know) Forget the 32 bit, Debian 64 bit will be rewarding enough.
One more tidbit, you only have a 1gb swap. Dang Morten if you have a 250gb hdd, bump that swap up to 2gb. Any larger may create memory leaks, (loops) but 2gb will work just fine. These OS's , like OpenSolaris and Debian 64, are big and will enjoy a larger swap file.
So here is my suggestion for your hdd layout:
/dev/sda1 #20gb WindowsXP
/dev/sda2 # 2gb SWAP
/dev/sda3 #100gb Debian 64
/dev/sda4 #125gb OpenSolaris
Take note: this equals 247gb, that is beause your hdd is probably not going to be 250gb exact, it will be close but not exact. This also allows a little space for block checks and other things that you may need a little room for later.
Also, notice that Windows is only 20gb, that because you are stepping up to another level. You are going to use windows less and less; and either Debian or OpenSolaris more and more. Be advised there are major differences between Debian and OpenSolaris, so it may be prudent to select one that you favor and immerse yourself in it.
These selected OS's are a smart sampling of what is running on most computers today. There is one more you may consider, I enjoy it quite a bit. That is Menuet. This is a 64 bit OS running on Assembly, built on FASM. You can download it to a floppy and run it off that floppy, OR you can take the image file, put it on the C:\ drive in windows and boot off it there. so then you will have another OS to play with when you desire.
Last but not least, you may notice that OpenSolaris has 125gb. Well, you wouldn't take Paris Hilton to McDonalds would you??? Likewise with OpenSolaris, give her all she wants and she'll do you good. lol Whatever!
It would probably be best if you cleaned your disk and started fresh. Consider the OS's I suggest and perhaps get advice from someone else as well. It will work, but it may take a few tries.
Have fun,
Chooch