Well, you would need an adapter to be able to connect a 2½" notebook HDD to a standard desktop mobo's SATA port - notebook and desktop HDD's use different connectors and pinouts for both data and power. Then you'd need some adapter system to help you physically mount the smaller notebook unit in the desktop's drive slot. Once that is done you would have use of the notebook just as if it were a desktop type of unit.
At that point hypothetically you should be able to create a RAID0 array from the two drives. Although everyone says the ideal situation for RAID anything is matched identical drive units, you already have a match on speed and capacity, so maybe that's enough to get it to work OK. But you will have two things to address before committing to this plan. One is how you will get the data on your current desktop drive migrated to the new RAID0 array. Your RAID system utility software may help you with this, or not. Consult your RAID system manual on how this must be done.
The other item is, how do you boot the machine? If you have a third drive from which you boot now, and the new RAID0 array will just be for data, no problem. But if you plan to boot from the RAID0 array, you will probably have to "start from scratch". This is because, to boot from a RAID0 array, Windows will have to be freshly re-installed on that array to include RAID drivers (may need a floppy drive and disk for driver loading during Install). That means backing up all your current data. Then you create the array, Install Windows with the required RAID drivers, Install all your old application software and configure it, then restore from backup all your data files. Not quick and easy, but can be done if you understand and plan ahead.
By the way, what motivates you to go RAID0? Is it worth the effort?