I've been running the Asus P4PE since early December without any problems... Very stable!
Here's my setup:
- Lian-Li PC65 Case w/ Enermax PSU
Asus P4PE Mobo w/ Soundmax on board (Great sound!)
Intel P4 2.53 CPU Retail
512MB Corsair PC2700 DDR (x2)
WD 80GB Special Edition HDD
WD 30GB HDD
Lite-on 16x DVD
Lite-on 48/24/48 CDRW
ATI RADEON 9700 Pro
WinXP Pro SP1
Also, you wont notice any difference between 4X & 8X AGP.