Is it safe to upgrade to Parallels for Mac Desktop V5.0

I've purchased the upgrade to Parallels for Mac Desktop V5.0, but I am reluctant to upgrade, based on allthe negative reports I have read about how slow WinXP is after the upgrade.

Has anybody upgraded successfully. Any favorable reports? Has the Parallels team resolved the upgrade slowness issues?

I simply can't afford to be sidetracked, or waylaid if Parallels Desktop for Mac is not SOUND.

Please advise.