how do I get around the lack of available memory?

Try either running it in compatibility mode with something older (I run w/ compatibility for xp service pack 2).
If that doesn't work, you can try using the task manager to set it's process' affinity to only use one processor.

You can also try using this method, click on start or the windows key, then go to search on 2000/XP or just click on the search bar for Vista and type in msconfig.

Which will bring up the System Configuration then click on boot, then go to advanced options, then if you arent allready able to change amount of memory you want your pc/laptop to start with everytime you shutdown or restart then click the box left side of the Maximum Memory and with this you have to set it below 4 Gigs since thats what most people like the above answer says have so for example I put it at 1800 since anything above 2000 didnt work, then when you do that hit apply then ok, then it will ask you if you want to restart do that and hopefully when you go and load it up this time the memory error wont show up.

The downside is that the game wont look nearly what it should be at the highest setting or it wont even let you just good enough, with a pc or laptop which sucks but to me this was the only way to get around this awful bug and the game will still look pretty good for its age and this downgrade. Hope this helped.

I just stumbled upon this thread.
There is a simple solution on this website:

//iain.cx/articles/bloodlines/

This fix is also included in Wesp's famous unofficial patch, but if you do not want to use this patch download the simple patcher from the link above.