Near Conniption

I WANT A NEW SEWING MACHINE!! Whine. I'm having tension problems with this knit dress. I have consulted my manual about the proper tension for the stitch I am using, I'm using the right thread and even bought ballpoint needles.... what is wrong with this monster?!  This thing was just serviced like half a dozen garments ago... After 11 years together I feel like a bad seamstress because I've been eyeballing this http://www.amazon.com/SINGER-4423-Heavy-Sewing-Machine/dp/B003VWXZQ0/ref=sr_1_7?ie=UTF8&qid=1337119907&sr=8-7  because let's face it, I can''t afford a Bernina. Sad day. Then my dream of launching this wretched hunk of metal from my highest window can be fulfilled! Thank you, that is all.