A) you don't buy a Creative Labs sound card for sound quality, and in some instances you can tell the difference (some onboard (especially found on lower segment Intel boards) is just horrid) you buy it for it's feature set, including THX, along with 7.1, and the high quality that it can maintain for recording and toying with music, it's not about what the human can and cannot notice the difference between, it's about offloading work from the CPU (which it does) and about giving you better features/better recording quality (the Line-In on some onboard just sucks, while an Audigy 2 ZS/Plat. has many features, and supports more line-in, along with optical)
BUT
if your sourcing to an amplifier, optical/digital, DO NOT USE CREATIVE, use a different brand like M-Audio or Turtle Beach, as Creative is reported to have many issues with digital output to amplifiers
in addition, if your using an nForce3 or nForce4 for the systems (nForce3 is Athlon64 only, nForce4 is both Pentium 4 or Athlon64, and for the AMD it should be at least an nForce3, don't get a VIA chipset, it may be $10 cheaper, but you really get what you pay for with VIA (VIA is probably less likly to support the dual cored chips on their value chipsets also, but idk if nForce3 would support em either, so just get a Socket 939 nForce4 with an Athlon64)
also, in addition
PCIE is FASTER THAN AGP
it provides more bandwidth, and it provides the card with more electricity (meaning you don't need a molex connector for the card, at least for some) along with full duplex, compared to AGP 8x's half duplex (so basically PCIE can send it's maximum ammount of data into the card, while at the same time recieving it's maximum ammount of data from the card, while AGP is send, then recieve, plus PCIE has a higher max)
in SLI PCIE currently is running x8
which means 8 lanes
which is still slightly faster than AGP 8x (due to full duplex)
while x16 is twice the bandwidth or more
the only cards that suck on PCIE are the GeForce PCX, which are GeForce FX chips adapted over using the HSI bridge, and they don't do so well in 3D05 (their AGP versions do better)
but GeForce 6600, 6600GT, and Radeon X600Pro, X600XT and X700Pro (X600XT is comparable to 6600, X700Pro is comparable to 6600GT (can't remember if X700XT exists, if it does, it's the comparable one to 6600GT, can't be bothered to look that up right now though))
but those above cards are all rather quick
perform slightly better on PCIE (no adaption to AGP, and the higher bandwidth is nice (with AGP 8x your approaching the ceiling (AGP 4x is fine for 99.9% of all games (doom 3 is the exception) while PCIE you have more breathing room)
PCIE is supperior to AGP 8x
and the rumor on these forums that it costs dozens of times more is TOTAL CRAP
PCIE versions of MOST video cards are cheaper (cards designed for PCIE, not AGP adaptions)
PCIE equipped motherboards aren't so expensive (I believe their at the lowest in the $60 range...)
PCIE offers future expandability for the next generation of cards
so please, can we stop this whole "PCIE IS EVIL, LETS YELL AT IT UNTIL IT GOES AWAY" belief
and accept a few things:
A) PCIE is the new thing, it's the new wave, and the next generation of GPU's are all native PCIE, not AGP
B) PCIE is superior to AGP 8x, by leaps and bounds
C) PCIE is not expensive beyond all belief
D) on any computer costing over $700 PCIE should be included, with a PCIE graphics card
also
for your system
i'd suggest a new Intel Pentium D (newegg has them now, Tiger has the Athlon64x2 if you want one of those, but their more expensive) the dual 2.8GHZ one is around $313 (around the cost of a 3.4GHZ 6 series, or less)
it provides 64-bit
doesn't have HT, but it does have 2 2.8GHZ cores (so it's better than HT)
and it's avliable now
i'd suggest that for a CPU for the media PC for a few reasons:
A) it'll encode/render video and audio faster than almost any CPU (as it's like having 2 CPU's)
B) it'll provide a very powerful system
C) it keeps you on the cutting edge of technology, dual cored 64-bit CPU's are seeming to be the new wave, this is one of them