I currently have a MicroATX motherboard with a 300w PSU and Athlon 1800+ (I think) and an IDE drive. The system is too loud and I think costing me too much in electricity bills.

I have CentOS 5.2 installed on it and run Apache, MySQL, Zimbra, BIND, etc on it and its a small site with very little access. Basically just for me to learn on and have fun.

I would like to use my current hard drive but get something small, quiet, and that uses very little power, I would like to spend under $100 if possible, used is fine. Can anyone give me a suggestion on what might be good?

I know this is a late reply but . . .
I use these http://cgi.ebay.com/Mini-ITX-1-8GHz-iGo ... .m14.l1262

These use the p4 mobile chip so they are low wattage. Mine run around 32w with a hard drive. It has room in it for 1 hard drive and perhaps a slim cd. It also boots off the cf card just fine. It runs centos just fine. BTW I have no affiliation with andover, just a customer.

They advertise this as a HTPC on eBay; I don't think a single core Pentium M 1.8 GHz processor could handle 1080p or anything like that, but I have a very basic and not too demanding application for my low-end HTPC.

I'm looking for something small and quiet to surf the net and stream standard definition from Hulu, YouTube, etc. to my Toshiba tube TV, and to act as a picture and music server. Planning on something like MediaPortal or XBMC for a front end, so I think I would have to add a 2.5" hard drive to it. The integrated audio looks like its only stereo (fine for my use in this case).

Do you think it would work for that application? Its very tempting at just $99.

1.8GHz Pentium M is actually quite beefy for its age. It should have no problem keeping up with your application. Possible concerns, though:

I see only VGA out -- does your TV support this?

Noise -- CPU and Case Fan look like little buzzy things. Shouldn't be too loud given the low power footprint of the system, but likely won't be silent.

The VGA out is a problem; I may go with a used SFF PC from eBay that I can drop my Hauppauge TV card into instead.

Just a note, a P4 M is not the same as a Pentium M.

For a cheap, low-power replacement, you could go for an Atom / Dualcore Atom board and some DDR2. You could use your current HD, and it'd draw quite a bit less power than the older Athlon.

I'm sure the OP's already taken care of his desire, and fshagan's got a different issue, but I figure this could still be useful for anyone in a similar position as the OP: older AMD-based system, running Linux, with power consumption that seems too high (though the OP never measured for sure, I expect he'd have seen similar results as I did with my similar box). Athcool (which should be available in many standard repos -- was in Fedora 9's) would be a good thing to look into, as it can enable power saving on the chip, when it seems like it wouldn't be enabled otherwise.

After installing and enabling athcool recently on my Athlon XP 2400+ system (KM266-based motherboard, PATA DVD-RW, one PATA HDD), idle power consumption dropped from around 70W to about 32W (as shown by my UPS's display). The CPU heatsink fan was driving me nuts previously (it was something like 7 years old, so not too surprising) so I had removed it (didn't seem much in the way of replacement heatsinks for Socket A or quiet fans to swap in) and I had to run the Tri-Cools in the P182 at medium to try and avoid the CPU's going over 60C at idle. With athcool, the idle CPU temp dropped to around 45C with both Tri-Cools on low. If I put the system under heavy load I have no doubts the inside would become an oven with just that little fanless heatsink, but there's never any sort of load currently, so that's a risk I'm willing to take.

It seems like it's difficult to get consumption much lower than that with current chipsets (when I was looking at an Atom 330 setup, 30-35W seemed to be the consumption figure), so for anyone with an older AMD-based Linux setup, athcool (or any other method of enabling the CPU's power saving features) would be a free way of reducing power consumption and heat. For me, those 35W (24/7) translate to around $3/month in savings, and since I didn't spend anything on a new PSU or other hardware, I don't have a new purchase to "pay off". (But of course there's other factors that changing hardware can influence, and this method won't work for everyone.)