The first thing you will experience is that XP will not boot in your new system. This is because of the sudden hardware changes. It is possible to do a repair installation to correct this but probably not with your Gateway media. The repair installation option is available with a genuine XP disk from Microsoft and, if the repair installation is successful, it generally preserves your programs and data but rebuilds Windows specific components. You will also need to have your MB and other hardware drivers handy as XP will probably not have all of them. This is a risk so backup what you cannot afford to lose. The RAID and SATA support will not affect you if you do not use it but if you don't load the drivers they will be flagged as non functional in your hardware configuration. You may as well load the drivers anyway.
I had an old gateway system with Athlon 700 slot A, now I am building my own system with Athlon 64 2800+ and ASUS K8N motherboard and Kingston PC2700 512 Mb Ram, I am planning to remove my secondary Hard Drive (which I upgraded) from my gateway system which has my XP installation and try that as a primary on the new system that I am configuring, do you see any issues with this. Please send in your suggestions before I start on it. Also the motherboard supports RAID 0/1 with SATA support, but I will be using my IDE as primary, will that cause any issue.
Thanks for your input in advance.