|Windows 98 was a DOS kernel operating system while XP belongs to the NT family of environments like Vista and 7.|
If the legacy games are DOS applications you can install DOSbox (free) and then run them inside it.
If however they are Windows 9X ganes, you can try to run in Win 98 compatibility mode; if that fails, your last chance is to run them inside a virtual machine like MS Virtual PC (free and working under XP Home too). In this case however you need to install inside the virtual PC a legal copy of Windows 98, so you need to get the installation CD.
The setup is quite easy and result assured, but the guest OS must be on hand.