There are no driver changes for graphics drivers between SP2 and SP3 so a driver should work on either (and does in my personal experience). We only VALIDATE with SP3 and although there is always a possibility that there is an issue on SP2 that we do not see on SP3 however that is HIGHLY unlikely for the graphics driver. SP2 is not POR for us so SP2 specific issues (if any) would not have a high priority for us. In a case like that the answer would likely be "update to SP3".
Hope that helps.
I agree with the previous replies, it should work fine with SP2, but in terms of official support, i dont know whether you need to have SP3 running.
However, one more thing to check is the Errata for IEGD which can be downloaded from:
All the best,