WGA no longer supported on XP SP2?

Due to a virus, I wiped and reinstalled XP Home SP2 on a six-year-old Dell laptop. But I couldn't run Windows upgrades -- it kept trying to run Windows Genuine Advantage but never getting through the whole process to display the pass/fail result. I have a feeling it's perhaps because Microsoft support for XP SP2 ended July 13, 2010 (same date as Windows 2000!). By manually downloading and installing the SP3 service pack, I was able to finally get through Windows Update and WGA.