You don't really need a better card, unless you latency is a monster.
You need a nice pre-amp, as the inputs on cheap and/or computer cards are not suitable for guitars.
Get a cheap Midiman ou M-Audio (Midiman was M-Audio) pre-amp. Ebay has a lot of Audio Buddys at +-50USD. This will let amplify your guitar to line level, suitable for your card or even headphones or Hifi.
Now for the software, there are some free alternatives, please take a look at the following page, as it gives a few freeware examples:
http://guitarfx.info/index_1.html
Also try the Revalver and Amplitube demos and check ebay, there might be some on sale secondhand.
You could also use any music software and chain some effects (reverb, distortion, delay, flanger, etc.) to get any sound you're after. Even just a distortion unit can be enjoyable.
Another option is to get a mini-amp (some even run on batteries):
http://www.dolphinmusic.co.uk/category/guitars/guitar-amps/mini-amplification/
The Vox Amplugs might be just what you're after.