real vs virtual memory in Parallels Desktop 5 for Mac

Is there any way to configure more 'real' memory to Windows virtual machine if I purchase additional memory for my iMac? Currently have 4 GB total for my iMac, with 2GB assigned for Parallels/Virtual Memory/Configuration. 1800MB assigned to Virtual Memory under Windows/System/Advanced/Performance Options/Virtual Memory. I am having problems using Adobe Creative Suite 3 (Photoshop ad Bridge). It runs very slow for each and every step I click on. I am unable to run batch processing for several photos or folders. Also, I am sacrificing remaining iMac memory usage and speed.
('Real' memory vs 'Virtual' memory observed in Activity Monitor on iMac showed Photoshop and Bridge using 'real' memory in KBs vs 'virtual' membory as MBs, as I would assume is needed to run efficiently.)
Would appreciate any help!