Is it harmful for xp?

[vvs]

I am using  XP Pro (sp 2) .I have chanced the setting of system reservable  bandwidth from 20% to 0 (zero)% to increase the internet speed.Is it harmful for my computer?I don't want automatic update.I turn off auto update.So there is no need of bandwidth reservation. What is your thinking?

[BC_Programmer]

no chance of damage. unlikely to speed up your connection, either.

[pragma]

Like BC_Programmer said, no harm but most likely no benefit either.
And I would personally keep automatic update on, in order to get security updates as fast as possible. But I know there's mixed feelings about letting Microsoft install updates automatically... So whatever suits you. Just remember to mark Patch Tuesdays in your calendar then.