Will This Make My Computer Faster? (Adding Some Ram To It)

well I am using:
Pentium 4 1.7 ghz
Asus mb P4B (I don't know the exact model)
Ge-Force 4 mx 440
Hard Drive 24 gb

I am keeping the setup above, about ram atm I got:
2x 256 mb 133 mhz and a 1x 128 100 mhz
I am thinking about replacing the 128 mb 100 mhz for 2x 256 mb 133 mhz
so after all I will have 4x 256 mb 133 mhz

is it worth it? I am spending around $15 for 2x 256 mb 133 mhz, they are used stuff

I use computer for Internet, MSN/Aim, Diablo 2 LoD
sometimes when I open a lot of Firefox pages, MSN,Aim, some Diablo 2 LoD windows, the pc got a bit slow, will this solve my problem?

133 and 100mhz won't make a difference. but going to 2GB will make your system performace a bit better, but don't expect much. As the previous poster said.. it will make ur computer a bit smoother