VLAN Setup For 2 Different Broadband Connections

I have a general networking question regarding VLANS, multiple broadband connections and accessing PC's on both setups from each other.What I would like to do is have 2 broadband connections, one a cable connection and one a DSL connection. I would like to run them both through a Netgear FS-726T switch. Since the cable connection will go through a Linksys router giving out I.P.s in the range of 192.168.1.x and the DSL will probably use the same range, I would like to keep specific PC's connecting through the DSL connection and some other PC's specifically through the cable connection. I THINK that this can be done via the use of VLAN's set up on the Netgear switch but I am unfamiliar with setting them up. I've read through the manual and researched it online but I must be missing something.Due to the bandwidth limitations on the Comcast connection, I would like to avoid any data coming from the PC's on the DSL connection from going out through the cable connection (I do customer support for my business and want customers to be able to access files on my file server and also be able to back up their PC's online to my backup server but on the DSL connection. I will eat up my cable bandwidth in a hurry just from the backups alone. I would like to set up all the PC's with static I.P. addresses if possible. Now, I also need to be able to remotely access any of the PC's from outside my network (which I can do now) but I need to be able to access the cable connected PC's from the DSL connected PC's and vice versa.I have a feeling what I want to do is a mess and may not even be feasible. I have asked the networking personnel where I work but (primarily because they are arrogant SOB's) they won't even give me the slightest bit of information.