Which processor should i get for Pc2100 ram?

have an asrock p4v88 mother board. Its an old computer, but recently i've decided to extend its life by upgrading some parts. Anyway right now i have 1.5 g of ram all pc2100. My old processor is a p4 2.0ghz, socket 478. Since im pretty much limited to that, im left with either getting a p4 3.0 ghz at FSB 533mhz or a p4 3.0ghz at FSB800mhz (This one is actually cheaper than the other).

I know ideally that the ram timing and the FSB frequency should be at a 1:1 ratio but would the performance difference be really noticeable? My mother board supports Dual channel for the RAM, and i know that'll help a little for ratio that aren't 1:1. Which processor would i get a better performance out from? How much would their performance differ?

Get the "p4 3.0 ghz at FSB 533mhz"

Your RAM supports a 533FSB not 800FSB.

As a result, the FSB800Mhz chip will need to severly downclock if it even works.

"As a result, the FSB800Mhz chip will need to severly downclock if it even works."
So if the FSB 800mhz were to downclock would its performance degrade to lower than the p4 3.0ghz at FSB533mhz?

"Unless that MOBO maker specifically guarantees 800FSB support on that Via based board, it may not have a downclock option."
How would i be able to find out if it does? "http://www.asrock.com/mb/overview.asp?Model=P4V88" here's the site of my motherboard's specs.

"The real question is how much should you spend on upgrading old technology before a new build is in order?"
Well Since I'm not really a heavy gamer, I don't feel the need to make a new build. Besides I'm too busy with law school, and I just want to be able to play games when i have the time and not being swamped with readings.