Hi Kgkev
It seems speedster hasn't replied to your previous thread after the diagnostics he advised which I don't usually run.
Anyway, yes, RAM makes a difference for a new or old machine. On your system it'll depend on what your FSB is. If your CPU FSB is 400MHz, the RAM will run at PC2100. If it's 533MHz, the RAM will run at PC2700/PC2100. If it's 800MHz FSB then your RAM will run at any of the 2 including PC3200.
I'm not sure which you have, but it looks most likely as 533MHz FSB, in which case your system will default to running all PC3200 RAM at PC2700.
Your system only has 2x DIMM single channel slots, which run PC3200/PC2700/PC2100 RAM (2 x 1GB maximum).
Crucial recommend on what they retail. 1GB PC3200 RAM will also be compatible, as long as it's low density, isn't composed of double sided x16 chips, and has no issues alongside the older stick of RAM. To check if it is compatible, the manual has to be seen with the MB QVL.
The Micron stick will probably run, it will run alone anyway. I'm not sure if it'll run alongside your previous RAM stick though as we need to know the model# of the previous RAM to see if they're both compatible alongside each other.
Here's your MB Qualified Vendor List (RAM that is tested compatible by ASUS to run): P24:
http://dlsvr02.asus.com/pub/ASUS/mb/...98_p4p800s.pdf
Any one of those is tested to work.
Scan.co.uk is a very good retailer, and so is yoyotech.co.uk and overclockers.co.uk.
The eBay link item has expired but it will
not work, since it's cheap, low quality high density RAM --> hence the price.
ECC is just parity RAM - you don't need that.
1.5GB is plenty for you IMO.