Any decent interface that connects with USB and uses real ASIO should be just fine for the sound card..... Presonus, Focusrite, M-Audio, ROland, and a bunch of others all work well...

For the soft synth... on of the best investments you can make in a good synth is Kontakt by Native Instruments. The reasons why include... it is a solid, well designed synth. NI makes a ton of sounds for it. Third party vendors make a ton of sounds for it. It uses sampled sounds.

It comes out of the box with everything you asked for.... I think it's lacking a bit on modern drums since IIRC the drums is has in it are orchestral in nature...... BUT.... if you purchase the NI Komplete collection you get Battery which is the drum synth..... Kontakt and the Komplete collection are not cheap... but they are worth every dollar.

Another cool thing going on right now is the sale on the new Music Creator 7 by Cakewalk. It's selling for $20 and comes with drums, bass, piano, strings, guitar, TTS, and Sound center. Sound center is one of my favorite synths. It uses sampled sounds and the add on sound packs are grouped by like kind....and also sell for around $20 each. In addition, the new MC7 has a bunch of loops.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.