After install of MDK10, the bootloader gives me several options to boot. I did not make them, they are part of the standard install. I can not find any clear information about these options. I have read a few threads regarding this topic, but not many responses. (A complete NewB is asking this btw )

Anyway, below are my linux boot options.

linux (/boot/vmlinuz)
linux-nonfb (/boot/vmlinuz)
linux-i686-up-4GB (/boot/vmlinuz-i686-up-4GB)
linux-enterprise (/boot/vmlinuz-p3-smp-64GB)
linux-p3-smp-64GB (/boot/vmlinux-p3-smp-64GB) This is the default
2425-2smp (/boot/vmlinuz-2.3.25-2mdksmp)
263-7 (/boot/vmlinuz-2.6.3-7mdk)
failsafe (/boot/vmlinuz)

What are the differences in the options?

How does the system determine the default boot option (eg linux-p3-smp-64GB)?

When I boot into the default, most things seem to work correctly (except for 3D accel, but I have found threads I think will help with this), but when I boot into the first option (linux), the system hangs directly after the graphical loading display (status bar).

When I am running Linux, how can I quickly find out what Kernel I am running (e.g., 2.3.25 or 2.6.3, etc)?

If it makes a difference to the response, my Hardware is as follows:

MOBO - Asus A7N8X-Deluxe Rev.2 (nforce2)
Processor - Athlon XP 2800+
Video - ATI Radeon 9700Pro
Ram - Corsair 1GB Twinx PC3200
Primary Drive - WD 80GB JB
Sec Drive - WD 120JB
SATA Dreive - WD 36GB Raptor
CDRW - LiteOn 52x24x52x
DVDRW - Pioneer DVR-AO7U 8X

Thanks,
Jim

Answer the easy question first!
Open a console. $ uname -r
The output from this will give you your kernel version.

3D acceleration: You probably won't get any 3d apps up and running until you've installed drivers for your ATI card.

Bootloader options: Strange, you have far more than me. If the install has set the default at the option you've stated, then I'd say that configuration is the one most optimised for your system. Failsafe will load the bare minimum and dump you to a command prompt only. As for the others on your list, I'm none the wiser. I only have
Linux
Linux smp
Failsafe
on my bootloader.

EDIT
If I boot Linux smp (rarely) I've found that some applications aren't 'fully featured'.
Example; Kmix is missing some volume settings, Kwrite has tool options missing, minor differences like that.
HTH