O Wise one's can u give me some advise on Ram for my n

Hi there I am getting togeather specs for a new system, something around P4 2gig, 512mb of ram but my computer store has given me a Quote with 2x 256MB DDR PC2100 Ram, is this ok or should I be getting RD Ram, dont really know the differance so hope you can help.System should be something like this.Intel Pentium 4 2.0GHZ Northwood (512k)512mb Ram DDR or RD?Maxtor 60GB 7200rpm Hard drive.Leadtek g-force4 ti4600 graphics card.Sony 21inch CPD-G520 flatscreen monitor.Soundblaster live.Intel D845BGL mainboard.Can you give me advise if this is ok or should I change anything.Thanks in advanceBarry.