Yeah man - DO NOT open those.
It's most likely the sobig virus.
And if you don't already run one, get a easy to use software firewall like
Tiny Personal Firewall 2.0.15 (The last freeware version)
It will let you know when your programs like explorer.exe have been changed and also what programs are accepting and requesting connections (and allow you to block them).
It's like zonealarm, but better
