Running multiple windows environments on the same computer?

I'm running a Business Process Automation program on my laptop and I'm looking to increase my output. Basically, I've written a script within Automate (essentially a fancy macro) that will access the internet, download some data from work, load it into another program that processes it, and ultimately run it through some custom filters in photoshop that outputs a file. The process loops and repeats with new data. The speed of the entire process is pretty much at it's max on my budget laptop (Dell Inspiron 1300 - Celeron M 370 @ 1.50 GHz, 1GB DDR2 RAM, Crappy Integrated Graphics Card, Windows XP Home). That is to say, increasing the power of the laptop wouldn't increase my output since the only real delays are from necessary pauses that I have built into the automate script.

As it stands now, I'm running the script 24/7 on my laptop but would like to be able to run 2 or 3 more copies of the task simultaneously. I can't run the task multiple times simultaneous in the same windows environment since there all sorts of conflicts with interactivity actions.

I'm hoping to find a software solution so that I can run the task multiple times on the laptop, as opposed to a hardware solution (ie. buy more laptops and just run it on there).

What I'd like to do is have my laptop run the automate script in multiple windows virtual environments. I don't know if this is even possible. I tried using multiple user accounts, but the account that is not "active" doesn't seem to be actually running the script in the background after I switch over to the other account, even if I don't log off. I also tried a few "virtual desktop" programs but found that they were really just ways to extend desktop space and would not actually allow a program (ie. photoshop) to be run multiple times on the same system. Does anyone know of a way that I could have multiple windows shells running simultaneously on the same system or a similar software solution along the same lines?

Thanks in advance for any advice.