A7V, A7V133, A7PRO, A7VE
ftp://ftp.asuscom.de/pub/ASUScom/HANDBUCH/Motherboard/Socket_A/VIA_Chipset/
A7A266, A7A266-E
ftp://ftp.asuscom.de/pub/ASUScom/HANDBUCH/Motherboard/Socket_A/ALi_Chipset/
Your RAM is limiting the choice of boards that you can buy.
The boards mentioned above are older boards (Ebay maybe?).
The A7A266, for example, likely does not have a very friendly
AGP interface, and modern video cards may not work well with it.
A7A266 has memory slots for SDRAM and DDR (but not both at the
same time).
For the A7V boards, you may want to use Google, to read up on
them. They certainly work for people, but are not entirely
trouble free.
http://www.a7vtroubleshooting.com
I would dump the 256M PC133, and pick up a 512MB stick of DDR
memory. Or two 256MB sticks of DDR memory, if shopping for a
dual channel memory board. Crucial.com has 512MB PC3200 CAS3
for $80 for one stick or 256MB PC3200 CAS for $84 for two sticks.
Cheaper generic ram might work with some of the boards, but
be careful about the A7N8X (Nforce2) boards, as they are picky
about RAM when running at DDR400 (only a problem for you if
you were to buy a 3200+ at some point in the future).
With some DDR RAM in hand, you can buy any of the boards from
the current listing for "Socket A":
http://usa.asus.com/products/mb/mbindex.htm
A7N8X-E Deluxe - dual channel, picky about RAM $88
A7N8X-X - single channel, picky about RAM $65
A7N8X-VM/400 - not recommended (annoying video/ram issues)
These are probably not bad, and have an equal rating
VIA KT880 A7V880 - dual channel memory $66
VIA KT600 A7V600 - single channel memory
VIA KT600 A7V600-X - single channel memory $60
VIA KT400 A7V8X-X - single channel memory $53
VIA KM400 A7V8X-MX SE (not sure about this one - microATX)
VIA KM400A A7V400-MX - popular, google for info. $51
When a board has three memory slots, you cannot count on
being able to use all of them at DDR400 transfer rates.
The faster that a DDR memory bus is driven, the fewer
sticks that will work reliable. Download and read the manual
for any of these motherboards, before you buy them, to see
what restrictions are listed for sticks of RAM, or what
settings might be missing from the BIOS. Type in the model
number here, then select "All" for the info type. There
will be PDF manuals here to download:
http://www.asus.com.tw/support/download/download.aspx
This page tells you what processors a board can use:
http://www.asus.com.tw/support/cpusupport/cpusupport.aspx
HTH,
Paul