I try run my exe files on win 98. Then error somthin: "cant find gdiplus.DLL".
Then I find on my computer this file, copy and pase. And again run on win 98, then OK. 
So if you want run GDI+ exe on win 98 need "GdiPlus.dll" file. Size: 1.703.936 bytes. I thing you have it. else{search in google;}