@Stress- I have a buddy who has had Sins use up to 12 GB RAM on his 64-bit Linux.
Of course, he's got multiple quad-core processors, so that probably helps.
Not a alternative for the usual mister joe... first, you need a computer who allow hardware virtual machine ( my rig make it but his price tag is around 5000 euro, with a server board !!! )... second, you need Vmware ESX server ( around the 4000 $$$ )... using Linux was a other choice due to opengl caching the texture in the video ram in place of the main ram like directx... any way, the final limit was 1520mb by core... so, a usual dual core will not have any benefice ( cann use the /3g in your boot.ini for have 3gb for applicatio in place of the 2gb )...
Sins work very good with Linux and use fewer main ram but the problem is that a card with only 256 mb will not be able to store all the textures... a other problem is impulse, it don't work with Linux... but around one year ago, the online play with sins was resolved...
There is various way to push sins to his limit... and like i have say it numerous time before, the code is a little wonder... but all the work around cost money for the users, a bunch of it... nobody will by a several k$$$ rig or software for a single game...
Now, about a 64 bits sins, it is very possible to make it directly from the source... same thing with multicore... they are flag who can be enable at the compilation... point is that non optimised code will give a very poor win in performance... more bad will be a total desync between 32 bit and 64 bit version for online game... people already complain about a lobby for Ent and one for Diplomacy... now, imagine Ent32, Ent64, Dip32 and Dip64 lobby !!! ... this will fully kill the online play...
A last thing... 32bit or 64bit are only words... all 32 bits processor since the pentium pro are in fact 36 bits processor... and the new 64 bits processor are in fact 48 bits processor... more you pay for your OS, more your can access memory... a good old windows 2000 datacenter 32 bits edition can use 32gb ram... windows server 2003 datacenter 32 bits can use 128 gb... but who use a datacenter windows edition for game ?