As no one has replied, it looks like there isn't any chipsets for XP's supporting DDR ECC. What should I go for then?
P4 or MP or just throw away 2GB DDR ECC?
ECC is for servers and worstations. Thats why XP dont bother with it. It costs more and is slower then normal ddr. Cause its always checking data in ram for integrity.
Yes. But bear in mind that most ECC DIMMs these days are also registered. This is an electrically different arrangement, which also needs chipset support to work AT ALL. Typically, ECC-incapable chipsets do not have support for registered DIMMs either.