Sounds like you have a lot of issues going on here.
Here's an article to help with virtual memory:
http://www.delete-computer-history.com/increase-virtual-memory.html
You can try CCleaner, which I see some people here recommending but I myself don't recommend registry cleaners as they can cause more damage than they fix and they very rarely get all of the problems. A reformat and re-install of windows is much better and cleans the registry like no other registry cleaner out there.
As for your audio, it is compatible with both OS's. You just need to use the appropriate driver. Acer doesn't show anything for an aspire 9411 so I assume that the 9410 drivers will work. Do you have an install CD? Use that if you do.
Here is the download page, in case you need it.
http://us.acer.com/acer/service.do?...tx1g.c2att92=453&ctx1.att21k=1&CRC=2054404012
Note the different Vista and XP drivers.
Try re-installing your chipset drivers, then re-installing your audio drivers.
Try turning everything off that starts-up using msconfig (Start>>Run>>type in msconfig) and if things run better, turn on your start-up items one by one and see what is causing the conflict.
Let us know how it goes.
Pauldo