Well Doug, I have just come from the exact same system as you (P-3 600 98SE), in fact we're still using it daily. Remember back in Fall 1999, that was the hottest machine available? Two months later, 750's. Then the CPU's just started flying!Currently running an old P-3 600 98SE
Well I came to your same conclusions, and chose the Asus P4C800-E Deluxe mobo; 2.8 GHz/ 800FSB P4 CPU; 1Gig ECC RAM (2x Kingston #KVR400X72C3A/512). Also a True480 Antec supply; Lian-Li PC60 case; XP Pro SP1a; and other stuff. Except for some important offline Matrox P750 video problems, this rig has been solid so far. Better be, considering I spent 3 months planning it! Onboard sound, LAN, USB, COM1... I've tried everything but firewire so far, and it all works. I'm very happy!...am looking at the ASUS P4C800 Deluxe or Asus P4C800-E Deluxe boards. I plan on running a 2.8 CPU/1Gig ram...WinXP Pro.
It may not be an on-the-edge gamer's dream screamer --then again maybe it is-- but it should at least make a good audio-video editing DAW /networked office platform, with a little gaming. In fact, my whole design was around DAW needs, to begin with.
Don't get the non-E version of this mobo though; it lacks the ICH5R chip in case you ever want RAID from your Southbridge, also its LAN hangs off PCI instead of the Northbridge (North is better for the 1000 speed), and at least one guy hasn't been able to get his non-E LAN to work.
I also looked at 14 other mobo's, from 9 different mfg.'s and in case you care, my other top two choices were MSI 875P-Neo-FIS2R and the Gigabyte GA-8KNXP series. The MSI was it, right down to the wire when I was placing the order: I went back and forth between that and the Asus. As a vendor, Asus seemed to have more respect among OEM's and adapter vendors, and the mobo construction and layout seemed to be a half notch above the MSI. So I chose the Asus, not sorry either. If you DIY and can buy from Newegg.com, I can highly recommend them, after also dealing with KnowledgeMicro.
True there are many problems around here, but keep in mind that most people who aren't having trouble with their new rig, probably aren't coming here. I just built my new rig 10 days ago. I had success, so I'm hanging around trying to help others until my mobo becomes old news.After reading a few of the posts on the problems with the P4C800-E (the one I was planning on getting) I am starting to have second thoughts!
And also keep in mind, for stuff that doesn't work, everyone seems to agree Asus' customer support is utterly useless. So there's risk there, if you choose an Asus mobo. Slow website too. BUT support-wise there's probably risk regardless of whose mobo you choose, so I say go for the features you'll need now and for the next 4 years.
Multiple drives is a good idea: at least keep your data separate from your OS. Personally I chose all Maxtor Diamondmax+9 drives: one ATA-133 160GB (at ATA-100) partitioned 3 ways for the OS, and 3x SATA 160GB for non-RAID data and temp's. I had initially chosen Seagate drives, but from what I read later on, I would stay away from Seagate's for now, their performance does not seem to have kept up with the other players. Though your mileage may vary. Don't worry about the supposed 137GB upper limit on disk size-- universal patches are now available from WD....ATI Radeon 9600 Pro/ SB Audigy Platinium/ twin Seagate 120 SATA drives...
Don't know what to say about your proposed ATI video, except I seem to see lots of folks having video trouble with mobo's around here, as did I, so check around. I heard the Matrox G550 is fine with this Asus, but can't vouch for that.
More personal preference, I would also stay away from the Audigy, their ads are slick but if you want gaming, why not just use your software-based onboard sound? All the mobo's have it, and give you 5.1. But don't even try to use either for serious audio recording-- you can do WAY better with better-quality, non-Soundblaster hardware.
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Some other important details on my rig: Asus mobo BIOS 1007 saved & updated to 1010 (now 1011 is avail.); ACPI mode disabled in BIOS and XP installed in "Standard PC" mode; Hyperthreading disabled in BIOS; Boot device priority set to CD-Flop-HDD in BIOS.
Hope this helps,