Freewheel cogs interchangeable ?

[Pyrotechnic]

I have an older bike, from about 1998. I've ridden it for a long time and recently did a rear rack mount on the back. There's quite a bit more weight over the rear tire now. I was fixing a flat rear tire today and I found 2 spokes broken. The spokes are a little corroded/rusty since the bike sat outside for awhile before I decided to do the rack mount. Between the elements and their age, I think they are getting weak.

The other issue is the rear hub. The bearings sounds bad and feel rough. The free wheels cogs have some slop to them when moved by hand. It rides OK, but I'm not sure for how much longer considering the age and mileage of the bike.

I thought about having the rear wheel laced with new spokes and maybe a new hub, but then I found these:

http://www.amazon.com/Avenir-Alloy-...=sporting-goods&ie=UTF8&qid=1315953510&sr=1-8

http://www.amazon.com/Avenir-Alloy-...sporting-goods&ie=UTF8&qid=1315953510&sr=1-11

I'm thinking I could buy either of those wheels for much cheaper than what it would cost to rebuild my current wheel.

The big question is, can I take off the freewheel cogs from my current wheel and install them on the new wheel?

The derailleur setup is a Shimano SIS. The freewheels cogs have "EPOCH INDEX SPROCKETS BY DNP LY-1007 KF " stamped on then. There are 7 cogs on it.

The first wheel says 7 speed compatible. The second one doesn't say anything about compatibility, but I was leaning towards getting it since it seems to be a tougher wheel.

Will either of these wheels work?