If you dont have any games on Windows 7 and if you want to play Solitaire, you should copy cards.dll from:
windows xp > windows > system32
windows 7 > windows > system32
Then open sol.exe for regular solitaire, spider.exe for Spider Solitaire, mshearts.exe for Hearts, freecel.exe for Freecel (duh), winmine.exe for minesweeper and i cant find the other games but thats about it...
I included a ZIP for you if you dont have XP anymore. just extract the dll to your system32 folder