Calibrating Color in Windows XP to view PDFs from Mac version of IDCS3

Question

I have a customer in another city and all of their staff, who work with me, use Windows XP on Dell desktops with Dell LCD flat displays.
Four the past four years they have been happy with reviewing my designs as Review PDFs, exported from InDesign CS, CS2 and CS3, and initiated for review and comment with Acrobat 7 Professional. They have been satisfied with the color representation from viewing my PDFs on their screen, with free Adobe Reader, and they like the speed and cost cutting that results from not requiring a printed calibrated color proof to sign off on before going to press. When I export to PDF from InDesign, I make my Destination Profile "U.S. Web Coated (SWOP) v2" and I include the Destination Profile.
Then I designed a poster for them that was mostly teal (a color between green and blue. They saw the color as medium blue on their screens and approved job to go to press. They were disappointed to find the final printed pieces looking teal.
I know there is expensive third party calibration software out there but is there adequate color calibration for my non-technical customers using Windows XP on Dell LCD Displays?
I use Apple CRT Displays an I use the OS X System Preferences/Displays dialog to set my color temperature to 65000 and my Gamma to 1.8 and then I use the slider controls to adjust for the ambient light in my office. The color I see on my monitor is the same color I get when my design projects come off the printing presses.
Does Windows XP have software monitor controls to give the Dell workstations basic generic color calibration? Does XP let the user adjust the color temperature and Gamma settings?

Answer 1

Thank you all for your advise.
In the earlier part of this decade I required customers to sign off on a calibrated color contract proof. It was either a Fiery or an Iris color proof, before the job went to film separations. Then I would have the costumer view a match-print made from the film separations. Then the printers went to direct to plate PostScript imaging after I started my own design studio.
I used Adobe PressReady software RIP with my Epson Stylus Photo 1200 to make pre flight proofs that were a dead-nuts representation of what we would eventually receive off the printing press.
With InDesign and Acrobat providing onscreen separation & overprint previews, the need for me to see match-prints went away and that process moved more into the hands of the printer since they were doing direct to plate pre press imaging in-house.
I have color corrected all the photos I use to provide eye-pleasing-color on the printing press. The customers were happy to omit the printed proof stage to save on costs and the printers liked using just PDFs for customer approval because they liked my color correction and they wanted to speed up the process of getting the job approved and onto the press.
In this recent unique circumstance, my customer picked and purchased the stock art for the background of his flyer and mail card which I produced for him. I used InDesign's eye-dropper tool to make the display type the same color as the dominant highlight color in the stock art.
This is a circumstance were a printed color proof would be best and since this customer has a creative eye for color, I will probably ship color proofs to him in the future. I plan to keep the status quo with my other customers, using only emailed PDFs for review because it has been successful this way for a long time and it avoids the cost of color proofs, next day shipping, and lets me work quickly with customers and printers that are hundreds of miles away because of the customers' email accounts and the printers' FTP servers.
I appreciate all the input I have received in these forums.
Rob