Effects of Partitioning A Hard drive

I would like to partition my hard drive for loading another Operating System(Ubuntu), and I was wondering if there was any geeks around YWS that would like to share their experiences. My main questions are just:

Does it slow the computer noticeably?
and
Do I need a boot disk after removing the partition(is it fully possible to even remove the partition?) to restore my main OS?

I can probably figure out the how, so I'm not worried about that right now.

I have some knowledge in this because I dualbooted Windows 7 and Ubuntu a while back...

To your first question, no, no it doesn't. In the slightest. You get the same power of the hardware, just the memory is split up.

For Windows 7, yes. You'll have to make a boot disk for that because after you remove the Ubuntu partition, the grub boot manager will search for the ubuntu partition and, when it doesn't find it, will go in a loop. What you have to do is pop the boot disk in, after you removed the partition of course, and repair the boot manager. There's some command prompts for this - Google is your friend.

But, if you're going to delete the partition, why don't you just run the live version on a USB? That way, there's no partitioning work, it just runs off the USB?

The USB thing sounds good, but then I get slow write speeds. I do have an Esata port and from my knowledge, that's for an external hardrive, but I'm dirt poor, so I don't have the money to buy one(again with the USB I don't have money to buy a new one).

And with the boot disk, could that still be made after the partition's created? And, if I scrap Windows for Ubuntu, would I need a boot disk or something for Ubuntu(can I even scrap windows)?

Edit: *facepalm* I'm stupid. I kinda need a boot disk to load the operating System in the first place. So yeah, I assume I need a boot disk.