32bit 33Mhz PCI bus limit is : 133MBytes/sec
Most current motherboard support that version of PCI.
While it is possible for 4 hard drives operating at maxs to saturate that. The chances of it actually causing your computer to slow down, I think, would be slim. Since you're transfering that much data off the hard drives, whatever you're transfering would go through quite quickly. Unless you need to quickly shove 10GB through in a matter of seconds, I doubt you'll notice any actual bottlenecking.
Most of the time, video editing doesn't rely alot on raw disk performance(unless you're working with uncompressed source). So while playing back that divx file, or encoding that video, it's only going to use a small SMALL percentage of your hard drive i/o.
Your CPU is most likely going to be the limiting factor in how quickly you produce video.
I would suggest you not go with a RAID setup. A) Finding 30GB drives that provide as much performance as current drives would be a pain B) 30GB cost more per GB then their higher capacity cousins C) More drives = more moving parts = greater chance of one of them dying and with RAID0, that means if one dies, ALL THE DATA ON THE OTHER DRIVES DIE WITH IT.
For the price of four 30GB drives & a RAID controller, you could get two Western Digital 120GB 7200RPM drives with a 8MB cache. These are good fast, reliable drives. With two of them you'll have twice as much hard drive as the four 30GB as well. :\
Then the CPU comes into play. I run a 1.4Ghz Athlon XP. I get near realtime MPEG2 decoding through AVISynth. However, I like to add IVTC, 2DCleaning and a Bicubic or Lanzcos resize to it. That all adds up to more CPU cost. So my spiffy 20 something framerate goes down around 2 - 7fps.
However, I have PC133 Cas3 SDRAM(1280MB tho

) and a crappy SDRAM/DDR chipset motherboard. So if I had better memory and a better chipset I would probably get a bit better performance.
Currently the chipset leader is the Nforce2 with dual channel DDR memory. You'd want to get that if you were going to do a single processor system. As for dual processor systems, AMD is really the only option. Dual P4 Xeons are out of anyones price range. However with AMD, you'll have to pay a premium on the board and the memory. You must use Registered DDR memory with a dual Athlon. Registered memory is about 2x the cost of the bargin bin stuff.
I am not sure what "DMP" is, dual CPUs are known also as "SMP" that's the closest I can find that matches what you're saying there. Using a SMP system could help PCI bottle neck, since the SMP chipsets support either 64bit 33Mhz PCI or 32Bit 66Mhz PCI, which ups the bandwidth to 266MB/sec.
>_> took me a bit but I priced out some systems. Note that these prices are not solid, they could change day to day. They came off pricewatch and I used various vendors not just one, so you could save or spend $100 - $200. Also you must know how to build el computoro yourself, or have a friend who can.
Athlon XP 2400+ 1.93Ghz CPU @ 134 or 2100(1.67Ghz) + @ $80
Epox RDA Nforce2 Motherboard @ 92
2x 512MB Micron pc2700(333Mhz) @ 124(62ea)
2x 120GB Western Digital 7200RPM, 8MB cache @ $280(140ea)
Chaintech Geforce4 64MB ti4200 @ $110
Turtle Beach Santa Cruz @ $58.00
Lite-on 52X24X52 CDRW Drive @ 48
Lite-On 16X DVD Drive @ 35
350Watt AMD approved ATX case @ 35
Keyboard/Mouse/Floppy @ 30
------------------------
$946
$591 : 1.67Ghz, 512MB DDR, 1x 120GB hard drive
2x Athlon MP 2400+ 2.0Ghz CPUs @ 424(212ea) or
---or 2x Athlon XP 2400+ 1.93Ghz CPU @ 268 NOT GARUNTEED TO WORK!!!!
MS-6501 K7 Dual AMD Board @ 187
2x 512MB Micron REGISTERED pC2100(266Mhz) @ 152(76ea)
2x 120GB Western Digital 7200RPM, 8MB cache @ $280(140ea)
Chaintech Geforce4 64MB ti4200 @ $110
Turtle Beach Santa Cruz @ $58.00
Lite-on 52X24X52 CDRW Drive @ 48
Lite-On 16X DVD Drive @ 35
400Watt AMD approved ATX case @ 53
Keyboard/Mouse/Floppy @ 30
-------
$1377
$1161 1x 120GB, 1x 512MB
$1221 using non-approved XPs instead of MPs
$1005 using non-approved XPs instead of MPs, 1x 120GB, 1x 512MB
You could make it even cheaper. If you don't play games or don't really care about super-duper sound, you could just use the onboard sound and get a Geforce2mx card. That'd reduce the price about $137 on any of hte above systems.
~Most~ Athlon XPs work in MP mode, they have all the circuitry needed to work in dual cpu system. They are not tested by AMD to ensure that it works properly. In fact some say that Athlons that failed to work in a SMP setup but functioned fine as a single processor are relabeled as XPs.
I don't think you're saving enough money to justify going for XPs instead of MPs.
~klinky