Questions on SP1 cracks

Hi, google pointed me to an article on this site, and from there to this forum, and it seemed as good a place as any to ask about Vista SP1 cracks.

Long version first, shorter one after.
Started off with Vista 32bit with one of the time cracks, giving unlimited trial period, and that worked great untill I stupidly downloaded SP1. A quick search revealed working SP1 cracks, I downloaded one and installed it. Then, when booting, after the BIOS did its thing, there was a message about loading 'GRDLR' or something along those lines, I think its something to do with Grub, the linux bootloader. Anyway, that ran in a second or so, and then it gave the list of Windows versions to run (I have XP and Vista on 2 drives) and all was good.
Then, a couple of days ago I did some major hardware upgrading. New heatsink, new hard drive and 2Gb more of ram, bringing me to 4Gb. Installed all of them, tried to boot, and it kept failing to find boot devices. After much switching the hard drives around, I managed to boot into XP and remove the bootloader, and everything was fine again, except the vista was then uncracked.
Installed Vista 64 on the new drive, and it installed that bootloader again, and it seems to be fine. Still runs after the BIOS, and its worked for both the 32 and 64 bit versions of Vista.


So, I'm assuming that this crack is independant of the BIOS. I'm trying to overclock my CPU again, and I'm getting 10 tons of bluescreens. I'd like up try updating my BIOS, but I want to make sure that wouldn't mess up the crack first. I'm looking to get some good performance out of the CPU, so I'm not sure that a modified BIOS would help, as I saw someone's post saying the modded ones weren't so good for performance.
And how does the crack I'm currently using work? I'm assuming it makes Vista think the BIOS is somehow different, but could this be causing problems if I try to overclock?


tl;dr
How do the two main SP1 cracks work. The directly modified BIOS one and the one that loads once the BIOS is done, and could they affect the working of the PC in any way, especially with overclocking.

Thanks

Specs: Asus P5B
E6600
4Gb (4x1Gb) PC5600 RAM
X1950XT 512Mb graphics.