$7 a month is a pretty good deal for 40mins airtime (against currently available prepaid plans), but you probably also need to consider;
1. It's likely excluding System Access, E911 and perhaps the TTY fees.
2. It likely comes with a 2yr or 3yr commitment i.e. you're locked-in.
The monthly SAF and E911 will add about $6.95 and $1 to your bill respectively, taking your monthly outlay to around $15 - which @ 37.5cents/min, isn't so good for 40mins!!!
The other consideration is that you might not actually use 40mins every month, in which case a significant portion of your $15/month is a nice annuity for Ted.
The cheapest prepaid plans currently available run about 20 cents/min + $1 for E911 and no SAF. At that rate, it will cost about $9/month for 40mins, but only $5/month if you use only 20mins, so you only pay for what you actually use.
7-11 Speakout and PetroCanada both offer prepaid plans on the Rogers network @ 20cents/min plus E911 monthly fee. The downside is that you have to buy a new phone (cheapest is ~$60). The good thing is that small dollar top-up cards last for 1 year before expiring. The downsides are no US roaming and neither service offers internet based loading or customer service. You have to buy the top-up cards at retail outlets.
Another option, if you don't want to buy a new phone or want more flexibility is to get a Rogers SIM ($5 on eBay, $25 in store) and (re)activate your existing phone on their paygo network. Cost is a little higher @ 25cents/min, but you can roam in the US ($$$) and top-up your account and other stuff on the internet. In this case, only the $100 top-up comes with a 1 year expiry.
Note that for either of the prepaid options, you should be able to keep your existing phone number.