it depends on the RAID card. cheap RAID cards will be software based, similar to a software modem if you are familiar with them. that means not all have all the hardware controllers necessary to make them work (this makes them cheaper to make and buy) and part of the what is necessary to make them work is run as software by the operating system. if you get a completely hardware controller then you should be able to access it with a particular key during boot.
I need your help with this ! I'm willing to purchase a PCI RAID controler to ( Merge ) between my two ATA hard Drivers physically .
i'm not entirely certain what you mean by that. i hope you don't think that you can just merge the drives into a RAID. if there is already data on them you will either have to back it up or lose it. if you want to make a RAID 1 array and only one drive has data it is possible however given you need help i'm guessing you will be wanting a RAID 0 array as only people who already were familiar with RAID would have use for RAID 1