PhysX card [Please assist in answering my question]

Ok, I did search the forums and could not find anything (or might have used the wrong search string, I don't know), but I am going to be putting an Agia PhysX card (PCIEx1 [yes I know people say the PCIE 1x is slower then the 16X slots]) but I already have my two AGP slots filled and the remainning (accessible) PCIE 16x slots are used by a sound card and even though I can still fit one more card in the remainning slot im concerned the space between the card and the video card fan will be way to close for effective air flow, so the next best slot is one of the PCIE 1x slots.
now for the question, I have the drivers installed from the previous card (the physX drivers/software from nvidia) and the card for the PCIE1x (PCI? sorry i get confused some times) has the "agia physX" logo on it, but the source i got it from sais it was supposedly "dell branded" (sold by dell maybe?? I dont know), the drivers for physX should work regardless of the cards OEM manufacture, right? IE even though my other physX car is made/branded by Asus I shouldnt have issue with the dell (supposed) card being they are both from the same company?
I just want to figure it out before I go opening my case and install this thing and wind up with headaches I don't want...or worse...(and Incase its one of the "once opened you cant return it" type of items...but still that doesnt bother me much either)
sorry if this confuses anyone, im not the best when it comes to explainning my thoughts in words...always been an issue I have had...
now for the question, I have the drivers installed from the previous card (the physX drivers/software from nvidia) and the card for the PCIE1x (PCI? sorry i get confused some times) has the "agia physX" logo on it, but the source i got it from sais it was supposedly "dell branded" (sold by dell maybe?? I dont know), the drivers for physX should work regardless of the cards OEM manufacture, right? IE even though my other physX car is made/branded by Asus I shouldnt have issue with the dell (supposed) card being they are both from the same company?
I just want to figure it out before I go opening my case and install this thing and wind up with headaches I don't want...or worse...(and Incase its one of the "once opened you cant return it" type of items...but still that doesnt bother me much either)
sorry if this confuses anyone, im not the best when it comes to explainning my thoughts in words...always been an issue I have had...