laggy problem

[alice9]

my com spec is

msi k8 neo
ddr400 2x512mb ram
leadtek 6600 gt
western digital 40 gb
maxtor40 gb
power supply cooler master 430w
benq dvdr

i play games esp dota allstar, i sometimes felt laggy.... i dunno wat is the problem is hardware or net or wat.... izzit using lancraft got link to this problem...