Oh crap

That mother board has only 4 different DIMM slots (2 DIMM slots for SDR and 2 DIMM slots for DDR).
You can't mix them together so you have another problem.
SDR and DDR when it comes to price cost the same.
Solution 1: Buy 2 SDR memory 512Mb a peace
Solution 2: Buy 2 DDR memory 512Mb a peace
WARNING: i think they have to work on 133Mhz (check that on your
old memory sticks)
Eather way you have to get rid off old SDR stick because you cant
mix them or use them on that motherboard if thinking of upgrading.
TIP: try asking in some PC store or PC reapir shop do they accept
old memory sticks and in that way you can get at least some
compensation.
And yes it is a good guide. RAM is easy to install. Remember it can
go in just in one way, and you have to hear/see those little clips
on the side close when you insert properly.
If it doesnt go dont rape it, try turning it around.
Hope i helped you

But i think it would be realy, realy good for you, to find a friend or someone that has little more knowladge than you to see it and help you. At least to detect what type of RAM you need and what is the working "tact" of those RAMs.