Snad víš, jaká RAM tam byla a jakou sis přikoupil.PC2-5300 is the correct term for DDR2-667mhz. PC-5300 is an incorrect term or typo error.
Here are the correct terminologies:
PC-xxxx for DDR, e.g. PC-3200 for DDR-400
PC2-xxxx for DDR2, e.g. PC2-5300 for DDR2-667
PC3-xxxx for DDR3, e.g. PC3-8500 for DDR3-1066