Will Tomato allow me to do this on a WGR614L?

Hi to all,

I’m pretty new to all this staff so please take it easy with technical terms!  I have 4 PCs on my LAN and want to manage WAN traffic on them using a WGR614L and Tomato or other firmware, which I don’t have yet.  PCs will be connected to the switch ports 1,2,3 and 4. PCs 1 and 2 must have priority for all traffic as and when they require it with no limits.  PCs 3 and 4 however, must be limited in internet bandwidth they obtain, in accordance to the following rules:

In any given week, bandwidth limited to 2mbs download and 448kbt upload for the first 500MB of transfer.

After that, within the same week, reduced bandwidth of 1mbs download and 128kbt upload for the next 300MB of transfer.

After that within the same week, limited bandwidth of 512kbs download and 64kbt upload for any other transfers.

I appreciate your views and any tips you may be able to provide since this would be some cool traffic shaping for my network.  I have not purchassed the router yet so if the above can't be done at all, could anyone tell me what router to get and with what firmware.