Did a test what should i do about the ram?

I have optiplex GX620 system with intel chip i945

i did a test through crucial.com
and the results it give me are as follows;

DDR2 PC2-5300
Memory Type: DDR2 PC2-5300, DDR2 (non-ECC)
Maximum Memory: 4GB
Currently Installed Memory: 3GB
Total Memory Slots: 4
Available Memory Slots: 0
512MB DDR PC2-5300 (Samsung M3 78T6553EZS - CE6 DDR2-333 this through memtest)
512MB DDR PC2-5300 (super talent supertalent01 DDR2-333 this through memtest+)
1GB DDR PC2-6400 (Hynix semi conductor Hymp112u64c68-S6 DDR-400 through memtest+)
1GB DDR PC2-6400 (Hynix semi conductor Hymp112u64c68-S6 DDR-400 through memtest+)


Each memory slot can hold DDR2 PC2-5300 with a maximum of 2GB per slot.*
*Not to exceed manufacturer supported memory.

i need to know are these comparable or not as my startup loading is slow than shut down. most of the times it feels it is freezes little bit on opening browser, mutli browser on firefox and crome as well and even on running programs occasionally.
All of them have written 667mhz on outside.

also at the moment i have 512mb on same slot together and 1gb on same slot together meaning 1gb on 1 and 2 slot and 512mb on 3and4 slot. and this is from memtest+ using usb

intel i945p/g ecc isable - fsb:199mhz
setting: Ram: 266 mhz (ddr532mhz)/ cas: 4-4-4-12/dual channel.