I'm curious about your system specs. You say "PC". Please be more specific. You say "Photoshop CS". Do you mean CS1? And you say "Topaz" (that's the company name, not the product). Do you mean DeNoise?
Here are the system specs from their website:
"Windows
Windows XP or Windows Vista (32-bit and 64-bit)
1 GB RAM
Adobe Photoshop 7 through CS4, Adobe Photoshop Elements 1 through 7, or another editor that supports Photoshop plug-ins. These include: Irfanview, PaintShop Pro, etc."