computer components & hardware - PC components ::: A few hardware questions

Hi,

I have a few PC hardware questions for new technologies I don't quite
understand. I've been out of the new PC loop for several years, I'm finally
replacing my p3 600E system.

PCI-E ::: Can anyone tell me what PCI express is ... the difference between
a standard PCI slot etc ... what it will be used for?

DVD-RAM ::: My new DVD burner will support R/W DVD-RAM at 5x. I have no clue
what this means.

My new system specs as I have then planned are below. I would appreciate
your thoughts on this new system ... what components are thumbs up / thumbs
down etc.

MSI K8T Neo 2-R
- A 939 socket board. I have been told that Abit/Asus/Gigabtye are better
overclocking machines, but I don't intend on overclocking. Just want a good
board.

AMD 64 3500+
- It was suggested to me that the new 939 socket chips are faster. This was
also cheaper than any P4.

1GB Dual Channel Performance Series OCZ PC3500
- My retailer originally planned to install Samsung PC3200 RAM. For a little
more cash I could afford the OCZ RAM. I hope it's performs good.

74GB WD740 "Raptor" HDD
- I did my research on this drive and it seems to be the closest to SCSI
without going SCSI. It's an S-ATA drive at 10,000 RPM.

Maxtor Diamond Max 120GB HDD
- This will be my reserve drive for storage and backups etc.

CL Audigy 2
- A good sound card so I have been told.

Coolmaster Centurion 5 Case
- An attractive case, all black, with a big fan on the back.

Thermatake 480W PS
- My retailer told me this is a quiet PS and has lots of power.

ATI X800 PRO
- I couldn't find the XT PE cards ( none available in my area ) so I'll
settle on this for now.

Logitech "Elite" Wireless keyboard/Mouse Combo
- My retailer says that these newer Logitech models are as good as a corded
mouse and keyboard. I hope it's true as I do alot of gaming. I want good
response time.

If you see any red flags in the hardware I have chosen above I would really
like to know. I'm spending alot of money on this and don't want to cut
corners. When I say "red flag" I mean BAD hardware or it doesn't have good
compatibility with the other components I have chosen. Obviously I could go
even faster in the RAM and CPU choices, but it's just too much $$$ for a
slight increase in performance. Your thoughts are welcomed and valued. I can
change my order if needed. TIA

Robert