I've finally decided to upgrade

Originally in college I worked off a dell build p3/600mhz/128mb $2,200 back in the day special.

The last computer was built with the help of a coworker, amd athlon 1800 system with 256mb of geil ram, 9200 ATI card, and a biostar mobo

I'd like some input for a new system I plan on purchasing soon

I've come down to this

GIGABYTE GA-965P-DS3
E6400 Processor
Western Digital Caviar SE16 WD2500KS 250GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - OEM
SAPPHIRE 100189L Radeon X1900GT 256MB 256-bit GDDR3 VIVO PCI Express x16 VIVO HDCP
SeaSonic S12-500 ATX12V 500W
Hanns·G HW-192DJB Gloss Black 19" 5ms DVI Widescreen LCD Monitor

housed in the COOLER MASTER Centurion 5 CAC-T05-UW
as far as the ram I'm crossed

CORSAIR XMS2 1GB (2 x 512MB) 240-Pin DDR2 SDRAM DDR2 800
with either the 5-5-5-15 timings or 4-4-4-12 timing

something that has me confused is the stipulation on newegg

Notice: Only DDR2-800 memory supporting JEDEC approved 1.8V operation with timings of 5-5-5 or 6-6-6 is supported on Intel Desktop Boards based on Intel 965 Express Chipsets.

I'm not too familiar with memory, and haven't kept up with hardware in almost 7 years now. Any suggestions?

The corsair memory will work fine with the 965p chipset. It's timings are rated lower which is better than the minimal standard. You can run them at the higher settings if needed. Lower numbers=faster speed.