Help choosing CPU & MOBO (AMD 64)

Im looking at building an AMD 64 System.

When looking at components im getting abit comfusted with matchin BUS speeds for the mobo & processer.

For example

AMD Athlon 64 4000+ Socket 939 1MB

Cache Memory
Installed Size
1 MB

Type
L2 Cache

Processor
64-bit
64-bit

Bus Speed
2000 MHz

Cache Level 1 Size
128 KB

Clock Speed
2.4 GHz

Core Voltage
1.35 V/1.4 V

Performance Index
4000+

Processor Socket
Socket 939

With this processer wud i have to get a mobo with a fsb of 2000mhz?

and i dont really understand the L1 & L2 cache (if take it the higher the better). but cud someone give me a laymans term of this.

or any links to a website to help me

ALSO WHAT SHOULD I LOOK OUT FOR IN A MOBO, TO POSS FUTURE UPGRADE A CHIP TO A FX CHIP (WEN THEY COME DOWN IN £S ABIT).
Obviously i need to no if mobo is compatiable, but in terms of bus speeds

thanks


lee