Originally posted by: pxc
Originally posted by: farstar
Are replacement motherboards available? Will these take a high speed ie 2.8 Celeron?

you said "high speed". j/k
The chances of loading up the system with more and faster parts is limited if you bought an AGP/PCI slot model with a 150W PSU. The Celeron 2.8GHz isn't out yet, but it should work in any any of the SFF cases (150W or 220W PSU). But if the system has an AGP slot, the 150W PSU models probably won't work very well with a fast video card (e.g. 9700/9800/FX5800/etc) since the PSU would be overloaded.
The 9700/9800/FX5800 video cards consume 60W+, the Celeron 2.7GHz consumes around 67W, an optical drive consumes about 18W, a hard drive consumes around 15W and add a few watts for memory, fans, motherboard (those figures are for the components under load, reading and/or writing). That's a load of over 180W. If you stick to an AGP card that doesn't use an external power connector, that lowers the video card power draw to under 30W.
For your original question: I think a Celeron 2GHz or 2.2GHz would be a better choice for this system. It support FSB overclocking and a Celeron @ 2.66GHz (533MHz FSB) is faster overall than a stock Celeron 2.7GHz (400MHz FSB). I ordered one of the cases last night that had the 220W PSU and I'm going to use a Celeron 2GHz @ 2.66GHz.