I just bought a new Dell with Windows 7 preinstalled. I installed PCLOS 2009. I resized partitions and installed grub without any problems. The only issue I had at all is the partition editor showed Windows as sda3 and grub asked if it should use sda2 for Windows. I changed it to sda3 and it failed (I know Grub is 0 based to 2 is correct, but I was thrown off because it called it sda2). I had to go into menu.lst and change it. So my recommendation is let the installation pick the correct settings for Grub.
But I have rebooted many times (setting up both PCLOS and Windows with the correct software and backed up data). Grub had no problems switching to Windows or PCLOS.
Also, just an FYI, when you resize Windows partition, it is set to run chkdsk on restart of Windows so don't be surprised when that occurs followed by another reboot the next time you go into Windows.