I dont see why not if you sent them to them. Best to check with them though Its very very easy to add a SATA drive to a motherboard nowadays, just connect the cable + a sata power cable, slot the drive into an available drive bay. Obviously if you want the OS installed on one thats a diff matter, so yes, inquire although probs best to phone the sales team tomorrow (0844 499 4000)
Thanks Sleinous, I wouldn't see it being an issue for them if I sent them. I could put them in after I have it delivered but I would like them to go through the build and test - I know they are ok then.