Looking for comments on homemade router

Since I’m having some trouble with my current router and its software (3Com made a very good hardware to keep on the load, but sucky software that is not configurable), I’ve decided to replace it with something more customizable. After rejecting all the options I found at my usual supplier, since most are not configurable at all, I’ve decided that the solution is to build my own, using Gentoo. While hacking the WRT54GL is still in my TODO list, it’ll take too much time, especially given the mipsel architecture not be supported, so I wanted to move to something easier to manage.

I might be overly needy, but my list of requirement is actually a bit long: I want something whose operating system can be loaded on an inexpensive replaceable flash memory (so I can keep a “stable” safe backup, and an experimental one to work on), it has to run Gentoo (obviously), has to be able to work as wireless access point, with a mac address access list (I don’t care if the format does not allow comments, since I can just use a script to update it), and have at least three Ethernet ports for the LAN, and one for the WAN. Power consumption is a major problem, but even more so is noise: it has to stay in the minuscule hall we have and if it’s too noisy my mother would kick me out of the house (and I cannot move the connection anywhere else because of the bad tubing connecting the house).

I already looked around at MIPS based RouterBoards, and Soekris cards, it seems like they more or less go on with what I want, the former with microSD cards and the latter with CompactFlash, but the price tag actually scared me off; with Soekris boards, with wireless, would cost me around €300, without a chassis, a MIPS-based board would probably go down to €300 with case, but both are pretty much embedded hardware. With due consequences.

Tonight I looked into the most obvious thing: a standard PC in a small case with a passive heatsink for the CPU. A Celeron D based system and an HTPC chassis would cost me around €300, with three Realtek network cards (and another one integrated) and an Asus WL-130N card (based on rt25k chip). I already have a CF-IDE adapter, so that I don’t have to get. This would look like a good choice I guess, I would be able to use CF cards for keeping the gateway updated, I’d have the power of standard x86 at hand, with Gentoo and the ability to manage it similarly to the vservers.

And here I’m asking for lazyweb’s help: can somebody tell me about the status of the rt25k chipsets on Linux? In-kernel or externally? How do they work in AP mode? (hostapd I suppose is the software to use) Does the AP software have a mac access control list? Are there passive PSUs that don’t cost as much as the whole system? Are there better alternatives?

I’m currently of the idea that for the sake of maintaining it, having a standard PC as a router is the way to go for me; I have way too complex needs for the standard routers it seems (indeed being able to just configure everything as I want is probably my main requirement), and even OpenWRT and the like don’t really look like the good choice for me.

Can somebody help me with comments?