Do not put the tower on the floor, it is likely to be damaged from cleaning activities; it could easily get wet from spills or mopping and it will pick up lots of dirt and dust. It needs to be close to a power supply and allow access in and out for various cables. For example if you position under the chair you will need to run monitor cables and USB inputs under the floor to the tower.
Need More Help? The article above is an excerpt from The Emmott on Technology Tech Guide; Computers in the Treatment Room