A few things.
First, the XLR > 1/8 adapter is a galactically bad idea.
Second, if you go with something like the MXL you'll need phantom power and a halfway decent preamp. And when you fire it up you'll soon see the need for at least some kind of room treatment because condensor mics are quite a bit more sensitive than most dynamic mics. That said, for recording piano a good solution might be a pair of Naiant small diaphragm condensors. They are very inexpensive and a good value for the money. Again, they require phantom power and decent preamps to reach their full potential.
The MAudio FastTrack series are pretty popular and MAudio has generally done a good job of keeping their drivers current and stable, even on legacy gear.
Another consideration is the OS of your laptop. Vista has multiple known audio issues that don't present themselves in either XP Pro or Windows 7.
Third, buying a GOOD QUALITY USB or firewire interface is gonna be much more versatile and give better S/N ratio and generally better sound than using the onboard soundcard.
Fourth, even if you decide to go with the SM58 you'll get better results with an interface with built-in preamps than the internal soundcard solution.
Also, you shouldn't need a pop filter with the 58 because it has a pop filter built into the windscreen.
Lastly, beware of fake SM57's and 58's on Ebay and only buy from legit authorized dealers that will accept returns for mics damaged in shipping.
Reaper is a good choice for recording software and buying the Reaper Power book is a good idea too for those just starting out in recording. There are a lot of features in all of the various recording software solutions that aren't readily apparent, as well as suggestions for optimizing computers for digital audio and tips about recording in general.