HOW DO I COMPLIED LINUX KERNEL?

I'm trying to compile the new 2.6.17.7 kernel.  I compiled it successfully (well, almost successfully - worked but the VGA was screwed up - didn't care because all i do is ssh in the box anyway) once, but then when i tried again for a different system, it stops and gives me this crap:

drivers/built-in.o(.text+0xcda78): In function `stv0299_writeregI':
: undefined reference to `i2c_transfer'
drivers/built-in.o(.text+0xcdb9e): In function `stv0299_readreg':
: undefined reference to `i2c_transfer'
drivers/built-in.o(.text+0xcdc8f): In function `stv0299_readregs':
: undefined reference to `i2c_transfer'
drivers/built-in.o(.text+0xcef11): In function `cx22700_writereg':
: undefined reference to `i2c_transfer'
drivers/built-in.o(.text+0xcf015): In function `cx22700_readreg':
: undefined reference to `i2c_transfer'
drivers/built-in.o(.text+0xcf953): more undefined references to `i2c_transfer' follow
drivers/built-in.o(.text+0xdd5ba): In function `ttusb_probe':
: undefined reference to `i2c_add_adapter'
drivers/built-in.o(.text+0xdd6b5): In function `ttusb_probe':
: undefined reference to `i2c_del_adapter'
drivers/built-in.o(.text+0xdd6f6): In function `ttusb_probe':
: undefined reference to `i2c_del_adapter'
drivers/built-in.o(.text+0xdd717): In function `ttusb_probe':
: undefined reference to `i2c_del_adapter'
drivers/built-in.o(.text+0xdd7da): In function `ttusb_disconnect':
: undefined reference to `i2c_del_adapter'
make: *** [.tmp_vmlinux1] Error 1

WTF is i2c and why do I need it.  I tried recompiling with I2C support enabled in Device Drivers but I still get this crap.

Any ideas?

>>2
Damn right.
>>3
It's the same exact Debian Sarge net-install on both systems (unless they updated the compiler on me in between installs ... hmm...)

well, i added all the i2c drivers again and recompiled without doing a 'make clean' - well, it compiled and booted.

now, two problems:
- i have no console on the keyboard/vga at all.  it boots/works though (beep command is wonderful for making your computer make noises at you at various points in boot stage); ssh works, but i'm not even getting bootup messages on the screen.  i turned off vga support in the kernel thinking all i need for text on the screen is mda support, wrong i guess. 
- i saw a bunch of stuff about "LD [M] whatever.mod" thinking it did the modules, so i didn't do "make modules" before "make install".  But then my nat routing is not working, and "iptables -L" bitches about a missing module.  Maybe I'll try "make modules" again.  Eeep!

It boots like WAYYY faster now (like in 10 seconds instead of 3 1/2 minutes)...